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JavaScript Language Reference


Learn JavaScript Language Reference syntax codes and tags using the sample below.

JavaScript Language Reference syntax




CONTENTS


The first part of this reference is organized by object with properties and methods listed by the object they apply to. The second part covers independent functions in JavaScript not connected with a particular object, as well as operators in JavaScript.

The following codes are used to indicate where objects, methods, properties and event handlers are implemented:

  • C  Client JavaScript (Server JavaScript is not covered in this appendix)
  • 2  Netscape Navigator 2
  • 3  Netscape Navigator 3
  • I  Microsoft Internet Explorer 3

The anchor Object [C|2|3|I]

The anchor object reflects an HTML anchor.

Property

  • name  A string value indicating the name of the anchor. [Not 2|3]

The applet Object [C|3]

The applet object reflects a Java applet included in a Web page with the APPLET tag.

Property

  • name  A string reflecting the NAME attribute of the APPLET tag.

The area Object [C|3]

The area object reflects an clickable area defined in an imagemap. area objects appear as entries in the links array of the document object.

Properties

  • hash  A string value indicating an anchor name from the URL.
  • host  A string value reflecting the host and domain name portion of the URL.
  • hostname  A string value indicating the host, domain name, and port number from the URL.
  • href  A string value reflecting the entire URL.
  • pathname  A string value reflecting the path portion of the URL (excluding the host, domain name, port number, and protocol).
  • port  A string value indicating the port number from the URL.
  • protocol  A string value indicating the protocol portion of the URL including the trailing colon.
  • search  A string value specifying the query portion of the URL (after the question mark).
  • target  A string value reflecting the TARGET attribute of the AREA tag.

Event Handlers

  • onMouseOut  Specifies JavaScript code to execute when the mouse moves outside the area specified in the AREA tag.
  • onMouseOver  Specifies JavaScript code to execute when the mouse enters the area specified in the AREA tag.

The Array Object [C|3|I]

Provides a mechanism for creating arrays and working with them. New arrays are created with arrayName = new Array() or arrayName = new Array(arrayLength).

Properties

  • length  An integer value reflecting the number of elements in an array.
  • prototype  Provides a mechanism to add properties to an Array object.

Methods

  • join(string)  Returns a string containing each element of the array separated by string. [Not I]
  • reverse()  Reverses the order of an array. [Not I]
  • sort(function)  Sorts an array based on function which indicates a function defining the sort order. function can be omitted in which case the sort defaults to dictionary order. [Not I]

The button Object [C|2|3|I]

The button object reflects a push button from an HTML form in JavaScript.

Properties

  • enabled  A boolean value indicating if the button is enabled. [Not 2|3]
  • form  A reference to the form object containing the button. [Not 2|3]
  • name  A string value containing the name of the button element.
  • type  A string value relfecting the TYPE attribute of the INPUT tag. [Not 2|I]
  • value  A string value containing the value of the button element.

Methods

  • click()  Emulates the action of clicking on the button.
  • focus()  Gives focus to the button. [Not 2|3]

Event Handlers

  • onClick  Specifies JavaScript code to execute when the button is clicked.
  • onFocus  Specifies JavaScript code to execute when the button receives focus. [Not 2|3]

The checkbox Object [c|2|3|I]

The checkbox object makes a checkbox in an HTML form available in JavaScript.

Properties

  • checked  A boolean value indicating if the checkbox element is checked.
  • defaultChecked  A boolean value indicating if the checkbox element was checked by default (i.e., reflects the chECKED attribute).
  • enabled  A boolean value indicating if the checkbox is enabled. [Not 2|3]
  • form  A reference to the form object containing the checkbox. [Not 2|3]
  • name  A string value containing the name of the checkbox element.
  • type  A string value reflecting the TYPE attribute of the INPUT tag. [Not 2|I]
  • value  A string value containing the value of the checkbox element.

Methods

  • click()  Emulates the action of clicking on the checkbox.
  • focus()  Gives focus to the checkbox. [Not 2|3]

Event Handlers

  • onClick  Specifies JavaScript code to execute when the checkbox is clicked.
  • onFocus  Specifies JavaScript code to execute when the checkbox receives focus. [Not 2|3]

The combo Object [C|I]

The combo object reflects a combo field into JavaScript.

Properties

  • enabled  A boolean value indicating if the combo is enabled. [Not 2|3]
  • form  A reference to the form object containing the combo. [Not 2|3]
  • listCount  An integer reflecting the number of elements in the list.
  • listIndex  An integer reflecting the index of the selected element in the list.
  • multiSelect  A boolean value indicating if the combo field is in multiselect mode.
  • name  A string value reflecting the name of the combo field.
  • value  A string containing the value of the combo field.

Methods

  • addItem(index)  Adds an item to the combo field before the item at index.
  • click()  Simulates a click on the combo field.
  • clear()  Clears the contents of the combo field.
  • focus()  Gives focus to the combo field.
  • removeItem(index)  Removes the item at index from the combo field.

Event Handlers

  • onClick  Specifies JavaScript code to execute when the mouse clicks on the combo field.
  • onFocus  Specifies JavaScript code to execute when the combo field receives focus.

The Date Object [C|2|3|I]

The Date object provides mechanisms for working with dates and times in JavaScript. Instances of the object can be created with the syntax

newObjectName = new Date(dateInfo)

Where dateInfo is an optional specification of a particular date and can be one of the following:

"month day, year hours:minutes:seconds"

year, month, day

year, month, day, hours, minutes, seconds

where the latter two options represent integer values.

If no dateInfo is specified, the new object will represent the current date and time.

Property

  • prototype  Provides a mechanism for adding properties to a Date object. [Not 2]

Methods

  • getDate()  Returns the day of the month for the current Date object as an integer from 1 to 31.
  • getDay()  Returns the day of the week for the current Date object as an integer from 0 to 6 (where 0 is Sunday, 1 is Monday, etc.).
  • getHours()  Returns the hour from the time in the current Date object as an integer from 0 to 23.
  • getMinutes()  Returns the minutes from the time in the current Date object as an integer from 0 to 59.
  • getMonth()  Returns the month for the current Date object as an integer from 0 to 11 (where 0 is January, 1 is February, etc.).
  • getSeconds()  Returns the seconds from the time in the current Date object as an integer from 0 to 59.
  • getTime()  Returns the time of the current Date object as an integer representing the number of milliseconds since January 1, 1970 at 00:00:00.
  • getTimezoneOffset()  Returns the difference between the local time and GMT as an integer representing the number of minutes.
  • getYear()  Returns the year for the current Date object as a two-digit integer representing the year minus 1900.
  • parse(dateString)  Returns the number of milliseconds between January 1, 1970 at 00:00:00 and the date specified in dateString. dateString should take the format [Not I]

Day, DD Mon YYYY HH:MM:SS TZN

Mon DD, YYYY

  • setDate(dateValue)  Sets the day of the month for the current Date object. dateValue is an integer from 1 to 31.
  • setHours(hoursValue)  Sets the hours for the time for the current Date object. hoursValue is an integer from 0 to 23.
  • setMinutes(minutesValue)  Sets the minutes for the time for the current Date object. minutesValue is an integer from 0 to 59.
  • setMonth(monthValue)  Sets the month for the current Date object. monthValue is an integer from 0 to 11 (where 0 is January, 1 is February, etc.).
  • setSeconds(secondsValue)  Sets the seconds for the time for the current Date object. secondsValue is an integer from 0 to 59.
  • setTime(timeValue)  Sets the value for the current Date object. timeValue is an integer representing the number of milliseconds since January 1, 1970 at 00:00:00.
  • setYear(yearValue)  Sets the year for the current Date object. yearValue is an integer greater than 1900.
  • toGMTString()  Returns the value of the current Date object in GMT as a string using Internet conventions in the form
    Day, DD Mon YYYY HH:MM:SS GMT
  • toLocaleString()  Returns the value of the current Date object in the local time using local conventions.
  • UTC(yearValue, monthValue, dateValue, hoursValue, minutesValue, secondsValue)  Returns the number of milliseconds since January 1, 1970 at 00:00:00 GMT. yearValue is an integer greater than 1900. monthValue is an integer from 0 to 11. dateValue is an integer from 1 to 31. hoursValue is an integer from 0 to 23. minutesValue and secondsValue are integers from 0 to 59. hoursValue, minutesValue and secondsValue are optional. [Not I]

The document Object [C|2|3|I]

The document object reflects attributes of an HTML document in JavaScript.

Properties

  • alinkColor  The color of active links as a string or a hexadecimal triplet.
  • anchors  Array of anchor objects in the order they appear in the HTML document. Use anchors.length to get the number of anchors in a document.
  • applets  Array of applet objects in the order they appear in the HTML document. Use applets.length to get the number of applets in a document. [Not 2]
  • bgColor  The color of the document's background.
  • cookie  A string value containing cookie values for the current document.
  • embeds  Array of plugin objects in the order they appear in the HTML document. Use embeds.length to get the number of plugins in a document. [Not 2|I]
  • fgColor  The color of the document's foreground.
  • forms  Array of form objects in the order the forms appear in the HTML file. Use forms.length to get the number of forms in a document.
  • images  Array of image objects in the order they appear in the HTML document. Use images.length to get the number of images in a document. [Not 2|I]
  • lastModified  String value containing the last date of modification of the document.
  • linkColor  The color of links as a string or a hexadecimal triplet.
  • links  Array of link objects in the order the hypertext links appear in the HTML document. Use links.length to get the number of links in a document.
  • location  A string containing the URL of the current document. Use document.URL instead of document.location. This property is expected to disappear in a future release.
  • referrer  A string value containing the URL of the calling document when the user follows a link.
  • title  A string containing the title of the current document.
  • URL  A string reflecting the URL of the current document. Use instead of document.location. [Not I]
  • vlinkColor  The color of followed links as a string or a hexadecimal triplet.

Methods

  • clear()  Clears the document window. [Not I]
  • close()  Closes the current output stream.
  • open(mimeType)  Opens a stream which allows write() and writeln() methods to write to the document window. mimeType is an optional string which specifies a document type supported by Navigator or a plug-in (i.e., text/html, image/gif, etc.).
  • write()  Writes text and HTML to the specified document.
  • writeln()  Writes text and HTML to the specified document followed by a newline character.

The FileUpload Object [C|3]

Reflects a file upload element in an HTML form.

Properties

  • name  A string value reflecting the name of the file upload element.
  • value  A string value reflecting the file upload element's field.

The form Object [C|2|3|I]

The form object reflects an HTML form in JavaScript. Each HTML form in a document is reflected by a distinct instance of the form object.

Properties

  • action  A string value specifying the URL which the form data is submitted to.
  • elements  Array of objects for each form element in the order in which they appear in the form.
  • encoding  String containing the MIME encoding of the form as specified in the EncTYPE attribute.
  • method  A string value containing the method of submission of form data to the server.
  • target  A string value containing the name of the window that responses to form submissions are directed to.

Methods

  • reset()  Resets the form. [Not 2|I]
  • submit()  Submits the form.

Event Handlers

  • onReset  Specifies JavaScript code to execute when the form is reset. [Not 2|I]
  • onSubmit  Specifies JavaScript code to execute when the form is submitted. The code should return a true value to allow the form to be submitted. A false value prevents the form from being submitted.

The frame Object [C|2|3|I]

The frame object reflects a frame window in JavaScript.

Properties

  • frames  An array of objects for each frame in a window. Frames appear in the array in the order in which they appear in the HTML source code.
  • onblur  A string reflecting the onBlur event handler for the frame. New values can be assigned to this property to change the event handler. [Not 2]
  • onfocus  A string reflecting the onFocus event handler for the frame. New values can be assigned to this property to change the event handler. [Not 2]
  • parent  A string indicating the name of the window containing the frameset.
  • self  A alternative for the name of the current window.
  • top  An alternative for the name of the top-most window.
  • window  An alternative for the name of the current window.

Methods

  • alert(message)  Displays message in a dialog box.
  • blur()  Removes focus from the frame. [Not 2]
  • close()  Closes the window.
  • confirm(message)  Displays message in a dialog box with OK and CAncEL buttons. Returns true or false based on the button clicked by the user.
  • focus()  Gives focus to the frame. [Not 2]
  • open(url,name,features)  Opens url in a window named name. If name doesn't exist, a new window is created with that name. features is an optional string argument containing a list of features for the new window. The feature list contains any of the following name-value pairs separated by commas and without additional spaces:

toolbar=[yes,no,1,0] Indicates if the window should have a toolbar
location=[yes,no,1,0] Indicates if the window should have a location field
directories=[yes,no,1,0] Indicates if the window should have directory buttons
status=[yes,no,1,0] Indicates if the window should have a status bar
menubar=[yes,no,1,0] Indicates if the window should have menus
scrollbars=[yes,no,1,0] Indicates if the window should have scroll bars
resizable=[yes,no,1,0] Indicates if the window should be resizable
width=pixels Indicates the width of the window in pixels
height=pixels Indicates the height of the window in pixels

  • prompt(message,response)  Displays message in a dialog box with a text entry field with the default value of response. The user's response in the text entry field is returned as a string.
  • setTimeout(expression,time)  Evaluates expression after time where time is a value in milliseconds. The time out can be named with the structure:
    name = setTimeOut(expression,time)
  • clearTimeout(name)  Cancels the time out with the name name.

Event Handlers

  • onBlur  Specifies JavaScript code to execute when focus is removed from a frame. [Not 2]
  • onFocus  Specifies JavaScript code to execute when focus is moved to a frame. [Not 2]

The Function Object [C|3]

The Function object provides a mechanism for indicating JavaScript code to compile as a function. The syntax to use the Function object is functionName = new Function(arg1, arg2, arg3, ..., functionCode). This is similar to

function functionName(arg1, arg2, arg3, ...) {
   functionCode
}

except that in the former, functionName is a variable with a reference to the function, and the function is evaluated each time it is used rather than being compiled once.

Properties

  • arguments  An integer reflecting the number of arguments in a function.
  • prototype  Provides a mechanism for adding properties to a Function object.

The hidden Object [C|2|3|I]

The hidden object reflects a hidden field from an HTML form in JavaScript.

Properties

  • name  A string value containing the name of the hidden element.
  • type  A string value reflecting the TYPE property of the INPUT tag. [Not 2|I]
  • value  A string value containing the value of the hidden text element.

The history Object [C|2|3|I]

The history object allows a script to work with the Navigator browser's history list in JavaScript. For security and privacy reasons, the actual content of the list is not reflected into JavaScript.

Property

  • length  An integer representing the number of items on the history list. [Not I]

Methods

  • back()  Goes back to the previous document in the history list. [Not I]
  • forward()  Goes forward to the next document in the history list. [Not I]
  • go(location)  Goes to the document in the history list specified by location. location can be a string or integer value. If it is a string, it represents all or part of a URL in the history list. If it is an integer, location represents the relative position of the document on the history list. As an integer, location can be positive or negative. [Not I]

The Image Object [C|3]

The Image object reflects an image included in an HTML document.

Properties

  • border  An integer value reflecting the width of the image's border in pixels.
  • complete  A boolean value indicating if the image has finished loading.
  • height  An integer value reflecting the height of an image in pixels.
  • hspace  An integer value reflecting the HSPACE attribute of the IMG tag.
  • lowsrc  A string value containing the URL of the low-resolution version of the image to load.
  • name  A string value indicating the name of the Image object.
  • prototype  Provides a mechanism for adding properties an Image object.
  • src  A string value indicating the URL of the image.
  • vspace  An integer value reflecting the VSPACE attribute of the IMG tag.
  • width  An integer value indicating the width of an image in pixels.

Event Handlers

  • onAbort  Specifies JavaScript code to execute if the attempt to load the image is aborted. [Not 2]
  • onError  Specifies JavaScript code to execute if there is an error while loading the image. Setting this event handler to null suppresses error messages if an error does occur while loading. [Not 2]
  • onLoad  Specifies JavaScript code to execute when the image finished loading. [Not 2]

The link Object [C|2|3|I]

The link object reflects a hypertext link in the body of a document.

Properties

  • hash  A string value containing the anchor name in the URL.
  • host  A string value containing the host name and port number from the URL.
  • hostname  A string value containing the domain name (or numerical IP address) from the URL.
  • href  A string value containing the entire URL.
  • pathname  A string value specifying the path portion of the URL.
  • port  A string value containing the port number from the URL.
  • protocol  A string value containing the protocol from the URL (including the colon, but not the slashes).
  • search  A string value containing any information passed to a GET CGI-BIN call (i.e., an information after the question mark).
  • target  A string value containing the name of the window or frame specified in the TARGET attribute.

Event Handlers

  • moveMouse  Specifies JavaScript code to execute when the mouse pointer moves over the link. [Not 2|3]
  • onClick  Specifies JavaScript code to execute when the link is clicked.
  • onMouseOver  Specifies JavaScript code to execute when the mouse pointer moves over the hypertext link.

The location Object [C|2|3|I]

The location object reflects information about the current URL.

Properties

  • hash  A string value containing the anchor name in the URL.
  • host  A string value containing the hostname and port number from the URL.
  • hostname  A string value containing the domain name (or numerical IP address) from the URL.
  • href  A string value containing the entire URL.
  • pathname  A string value specifying the path portion of the URL.
  • port  A string value containing the port number from the URL.
  • protocol  A string value containing the protocol from the URL (including the colon, but not the slashes).
  • search  A string value containing any information passed to a GET CGI-BIN call (i.e., an information after the question mark).

Methods

  • reload()  Reloads the current document. [Not 2|I]
  • replace(url)  Loads url over the current entry in the history list, making it impossible to navigate back to the previous URL with the back button. [Not 2|I]

The Math Object [C|2|3|I]

The Math object provides properties and methods for advanced mathematical calculations.

Properties

  • E  The value of Euler's constant (roughly 2.718) used as the base for natural logarithms.
  • LN10  The value of the natural logarithm of 10 (roughly 2.302).
  • LN2  The value of the natural logarithm of 2 (roughly 0.693).
  • LOG10E  The value of the base 10 logarithm of e (roughly 0.434).
  • LOG2E  The value of the base 2 logarithm of e (roughly 1.442).
  • PI  The value of pi-used in calculating the circumference and area of circles (roughly 3.1415).
  • SQRT1_2  The value of the square root of one-half (roughly 0.707).
  • SQRT2  The value of the square root of two (roughly 1.414).

Methods

  • abs(number)  Returns the absolute value of number. The absolute value is the value of a number with its sign ignored so abs(4) and abs(-4) both return 4.
  • acos(number)  Returns the arccosine of number in radians.
  • asin(number)  Returns the arcsine of number in radians.
  • atan(number)  Returns the arctangent of number in radians.
  • atan2(number1,number2)  Returns the angle of the polar coordinate corresponding to the Cartesian coordinate (number1, number2). [Not I]
  • ceil(number)  Returns the next integer greater than number-in other words, rounds up to the next integer.
  • cos(number)  Returns the cosine of number where number represents an angle in radians.
  • exp(number)  Returns the value of e to the power of number.
  • floor(number)  Returns the next integer less than number-in other words, rounds down to the nearest integer.
  • log(number)  Returns the natural logarithm of number.
  • max(number1,number2)  Returns the greater of number1 and number2.
  • min(number1,number2)  Returns the smaller of number1 and number2.
  • pow(number1,number2)  Returns the value of number1 to the power of number2.
  • random()  Returns a random number between zero and one.
  • round(number)  Returns the closest integer to number-in other words rounds to the closest integer.
  • sin(number)  Returns the sine of number where number represents an angle in radians.
  • sqrt(number)  Returns the square root of number.
  • tan(number)  Returns the tangent of number where number represents an angle in radians.

The mimeType Object [C|3]

The mimeType object reflects a MIME type supported by the client browser.

Properties

  • type  A string value reflecting the MIME type.
  • description  A string containing a description of the MIME type.
  • enabledPlugin  A reference to a plugin object for the plug-in supporting the MIME type.
  • suffixes  A string containing a comma-separated list of file suffixes for the MIME type.

The navigator Object [C|2|3|I]

The navigator object reflects information about the version of Navigator being used.

Properties

  • appcodeName  A string value containing the code name of the client (i.e., "Mozilla" for Netscape Navigator).
  • appName  A string value containing the name of the client (i.e., "Netscape" for Netscape Navigator).
  • appVersion  A string value containing the version information for the client in the form
    versionNumber (platform; country)
    For instance, Navigator 2.0, beta 6 for Windows 95 (international version) would have an appVersion property with the value "2.0b6 (Win32; I)".
  • mimeTypes  An array of mimeType objects reflecting the MIME types supported by the client browser. [Not 2|I]
  • plugins  An array of plugin objects reflecting the plug-ins in a document in the order of their appearance in the HTML document. [Not 2|I]
  • userAgent  A string containing the complete value of the user-agent header sent in the HTTP request. This contains all the information in appcodeName and appVersion:
    Mozilla/2.0b6 (Win32; I)

Method

  • javaEnabled()  Returns a boolean value indicating if Java is enabled in the browser. [Not 2|I]

The Option Object [C|3]

The Option object is used to create entries in a select list using the syntax optionName = new Option(optionText, optionValue, defaultSelected, selected) and then selectName.options[index] = optionName.

Properties

  • defaultSelected  A boolean value specifying if the option is selected by default.
  • index  An integer value specifying the option's index in the select list.
  • prototype  Provides a mechanism to add properties to an Option object.
  • selected  A boolean value indicating if the option is currently selected.
  • text  A string value reflecting the text displayed for the option.
  • value  A string value indicating the value submitted to the server when the form is submitted.

The password Object [C|2|3|I]

The password object reflects a password text field from an HTML form in JavaScript.

Properties

  • defaultValue  A string value containing the default value of the password element (i.e., the value of the VALUE attribute).
  • enabled  A boolean value indicating if the password field is enabled. [Not 2|3]
  • form  A reference to the form object containing the password field. [Not 2|3]
  • name  A string value containing the name of the password element.
  • value  A string value containing the value of the password element.

Methods

  • focus()  Emulates the action of focusing in the password field.
  • blur()  Emulates the action of removing focus from the password field.
  • select()  Emulates the action of selecting the text in the password field.

Event Handlers

  • onBlur  Specifies JavaScript code to execute when the password field loses focus. [Not 2|3]
  • onFocus  Specifies JavaScript code to execute when the password field receives focus. [Not 2|3]

The plugin Object

The plugin object reflects a plug-in supported by the browser.

Properties

  • name  A string value reflecting the name of the plug-in.
  • filename  A string value reflecting the file name of the plug-in on the system's disk.
  • description  A string value containing the description supplied by the plug-in.

The radio Object [C|2|3|I]

The radio object reflects a set of radio buttons from an HTML form in JavaScript. To access individual radio buttons, use numeric indexes starting at zero. For instance, individual buttons in a set of radio buttons named testRadio could be referenced by testRadio[0], testRadio[1], etc.

Properties

  • checked  A boolean value indicating if a specific button is checked. Can be used to select or deselect a button.
  • defaultChecked  A boolean value indicating if a specific button was checked by default (i.e., reflects the chECKED attribute). [Not I]
  • enabled  A boolean value indicating if the radio button is enabled. [Not 2|3]
  • form  A reference to the form object containing the radio button. [Not 2|3]
  • length  An integer value indicating the number of radio buttons in the set.
    [Not I]
  • name  A string value containing the name of the set of radio buttons.
  • value  A string value containing the value a specific radio button in a set (i.e., reflects the VALUE attribute).

Methods

  • click()  Emulates the action of clicking on a radio button.
  • focus()  Gives focus to the radio button. [Not 2|3]

Event Handlers

  • onClick  Specifies JavaScript code to execute when a radio button is clicked.
  • onFocus  Specifies JavaScript code to execute when a radio button receives focus. [Not 2|3]

The reset Object [C|2|3|I]

The reset object reflects a reset button from an HTML form in JavaScript.

Properties

  • enabled  A boolean value indicating if the reset button is enabled. [Not 2|3]
  • form  A reference to the form object containing the reset button. [Not 2|3]
  • name  A string value containing the name of the reset element.
  • value  A string value containing the value of the reset element.

Methods

  • click()  Emulates the action of clicking on the reset button.
  • focus()  Specifies JavaScript code to execute when the reset button receives focus. [Not 2|3]

Event Handlers

  • onClick  Specifies JavaScript code to execute when the reset button is clicked.
  • onFocus  Specifies JavaScript code to execute when the reset button receives focus. [Not 2|3]

The select Object [C|2|3]

The select object reflects a selection list from an HTML form in JavaScript.

Properties

  • length  An integer value containing the number of options in the selection list.
  • name  A string value containing the name of the selection list.
  • options  An array reflecting each of the options in the selection list in the order they appear. The options property has its own properties:

defaultSelected A boolean value indicating if an option was selected by default (i.e., reflects the SELECTED attribute).
index An integer value reflecting the index of an option.
length An integer value reflecting the number of options in the selection list.
name A string value containing the name of the selection list
selected A boolean value indicating if the option is selected. Can be used to select or deselect an option.
selectedIndex An integer value containing the index of the currently selected option.
text A string value containing the text displayed in the selection list for a particular option.
value A string value indicating the value for the specified option (i.e., reflects the VALUE attribute).

  • selectedIndex  Reflects the index of the currently selected option in the selection list.

Methods

  • blur()  Removes focus from the select list. [Not 2|3]
  • focus()  Gives focus to the select list. [Not 2|3]

Event Handlers

  • onBlur  Specifies JavaScript code to execute when the selection list loses focus.
  • onFocus  Specifies JavaScript code to execute when focus is given to the selection list.
  • onChange  Specifies JavaScript code to execute when the selected option in the list changes.

The String Object [C|2|3|I]

The String object provides properties and methods for working with string literals and variables.

Properties

  • length  An integer value containing the length of the string expressed as the number of characters in the string.
  • prototype  Provides a mechanism for adding properties to a String object.
    [Not 2]

Methods

  • anchor(name)  Returns a string containing the value of the String object surrounded by an A container tag with the NAME attribute set to name.
  • big()  Returns a string containing the value of the String object surrounded by a BIG container tag.
  • blink()  Returns a string containing the value of the String object surrounded by a BLINK container tag.
  • bold()  Returns a string containing the value of the String object surrounded by a B container tag.
  • charAt(index)  Returns the character at the location specified by index.
  • fixed()  Returns a string containing the value of the String object surrounded by a FIXED container tag.
  • fontColor(color)  Returns a string containing the value of the String object surrounded by a FONT container tag with the COLOR attribute set to color where color is a color name or an RGB triplet. [Not I]
  • fontSize(size)  Returns a string containing the value of the String object surrounded by a FONTSIZE container tag with the size set to size. [Not I]
  • indexOf(findString,startingIndex)  Returns the index of the first occurrence of findString, starting the search at startingIndex where startingIndex is optional-if it is not provided, the search starts at the start of the string.
  • italics()  Returns a string containing the value of the String object surrounded by an I container tag.
  • lastIndexOf(findString,startingIndex)  Returns the index of the last occurrence of findString. This is done by searching backwards from startingIndex. startingIndex is optional and assumed to be the last character in the string if no value is provided.
  • link(href)  Returns a string containing the value of the String object surrounded by an A container tag with the HREF attribute set to href.
  • small()  Returns a string containing the value of the String object surrounded by a SMALL container tag.
  • split(separator)  Returns an array of strings created by splitting the string at every occurrence of separator. [Not 2|I]
  • strike()  Returns a string containing the value of the String object surrounded by a STRIKE container tag.
  • sub()  Returns a string containing the value of the String object surrounded by a SUB container tag.
  • substring(firstIndex,lastIndex)  Returns a string equivalent to the substring starting at firstIndex and ending at the character before lastIndex. If firstIndex is greater than lastIndex, the string starts at lastIndex and ends at the character before firstIndex.
  • sup()  Returns a string containing the value of the String object surrounded by a SUP container tag.
  • toLowerCase()  Returns a string containing the value of the String object with all character converted to lowercase.
  • toUpperCase()  Returns a string containing the value of the String object with all character converted to uppercase.

The submit Object [C|2|3|I]

The submit object reflects a submit button from an HTML form in JavaScript.

Properties

  • enabled  A boolean value indicating if the submit button is enabled. [Not 2|3]
  • form  A reference to the form object containing the submit utton. [Not 2|3]
  • name  A string value containing the name of the submit button element.
  • type  A string value reflecting the TYPE attribute of the INPUT tag. [Not 2|I]
  • value  A string value containing the value of the submit button element.

Methods

  • click()  Emulates the action of clicking on the submit button.
  • focus()  Gives focus to the submit button. [Not 2|3]

Event Handlers

  • onClick  Specifies JavaScript code to execute when the submit button is clicked.
  • onFocus  Specifies JavaScript code to execute when the submit button receives focus. [Not 2|3]

The text Object [C|2|3|I]

The text object reflects a text field from an HTML form in JavaScript.

Properties

  • defaultValue  A string value containing the default value of the text element (i.e., the value of the VALUE attribute).
  • enabled  A boolean value indicating if the text field is enabled. [Not 2|3]
  • form  A reference to the form object containing the text field. [Not 2|3]
  • name  A string value containing the name of the text element.
  • type  A string value reflecting the TYPE attribute of the INPUT tag. [Not 2|I]
  • value  A string value containing the value of the text element.

Methods

  • focus()  Emulates the action of focusing in the text field.
  • blur()  Emulates the action of removing focus from the text field.
  • select()  Emulates the action of selecting the text in the text field.

Event Handlers

  • onBlur  Specifies JavaScript code to execute when focus is removed from the field.
  • onChange  Specifies JavaScript code to execute when the content of the field is changed.
  • onFocus  Specifies JavaScript code to execute when focus is given to the field.
  • onSelect  Specifies JavaScript code to execute when the user selects some or all of the text in the field.

The textarea Object [C|2|3|I]

The textarea object reflects a multiline text field from an HTML form in JavaScript.

Properties

  • defaultValue  A string value containing the default value of the textarea element (i.e. the value of the VALUE attribute).
  • enabled  A boolean value indicating if the textarea field is enabled. [Not 2|3]
  • form  A reference to the form object containing the textarea field. [Not 2|3]
  • name  A string value containing the name of the textarea element.
  • type  A string value reflecting the type of the textarea object. [Not 2|I]
  • value  A string value containing the value of the textarea element.

Methods

  • focus()  Emulates the action of focusing in the textarea field.
  • blur()  Emulates the action of removing focus from the textarea field.
  • select()  Emulates the action of selecting the text in the textarea field.

Event Handlers

  • onBlur  Specifies JavaScript code to execute when focus is removed from the field.
  • onChange  Specifies JavaScript code to execute when the content of the field is changed.
  • onFocus  Specifies JavaScript code to execute when focus is given to the field.
  • onSelect  Specifies JavaScript code to execute when the user selects some or all of the text in the field.

The window Object [C|2|3|I]

The window object is the top-level object for each window or frame and is the parent object for the document, location, and history objects.

Properties

  • defaultStatus  A string value containing the default value displayed in the status bar.
  • frames  An array of objects for each frame in a window. Frames appear in the array in the order in which they appear in the HTML source code.
  • length  An integer value indicating the number of frames in a parent window. [Not I]
  • name  A string value containing the name of the window or frame.
  • opener  A reference to the window object containing the open() method used to open the current window. [Not 2|I]
  • parent  A string indicating the name of the window containing the frameset.
  • self  A alternative for the name of the current window.
  • status  Used to display a message in the status bar-this is done by assigning values to this property.
  • top  An alternative for the name of the top-most window.
  • window  An alternative for the name of the current window.

Methods

  • alert(message)  Displays message in a dialog box.
  • blur()  Removes focus from the window. On many systems, this sends the window to the background. [Not 2|I]
  • close()  Closes the window. [Not I]
  • confirm(message)  Displays message in a dialog box with OK and CAncEL buttons. Returns true or false based on the button clicked by the user.
  • focus()  Gives focus to the window. On many systems, this brings the window to the front. [Not 2|I]
  • navigator(url)  Loads url in the window. [Not 2|3]
  • open(url,name,features)  Opens url in a window named name. If name doesn't exist, a new window is created with that name. features is an optional string argument containing a list of features for the new window. The feature list contains any of the following name-value pairs separated by commas and without additional spaces: [Not I]

toolbar=[yes,no,1,0] Indicates if the window should have a toolbar
location=[yes,no,1,0] Indicates if the window should have a location field
directories=[yes,no,1,0] Indicates if the window should have directory buttons
status=[yes,no,1,0] Indicates if the window should have a status bar
menubar=[yes,no,1,0] Indicates if the window should have menus
scrollbars=[yes,no,1,0] Indicates if the window should have scroll bars
resizable=[yes,no,1,0] Indicates if the window should be resizable
width=pixels Indicates the width of the window in pixels
height=pixels Indicates the height of the window in pixels

  • prompt(message,response)  Displays message in a dialog box with a text entry field with the default value of response. The user's response in the text entry field is returned as a string.
  • setTimeout(expression,time)  Evaluates expression after time where time is a value in milliseconds. The time out can be named with the structure
    name = setTimeOut(expression,time)
  • scroll(x,y)  Scrolls the window to the coordinate x,y. [Not 2|I]
  • clearTimeout(name)  Cancels the time out with the name name.

Event Handlers

  • onBlur  Specifies JavaScript code to execute when focus is removed from a window. [Not 2|I]
  • onError  Specifies JavaScript code to execute when a JavaScript error occurs while loading a document. This can be used to intercept JavaScript errors. Setting this event handler to null effectivly prevents JavaScript errors from being displayed to the user. [Not 2|I]
  • onFocus  Specifies JavaScript code to execute when the window receives focus. [Not 2|I]
  • onLoad  Specifies JavaScript code to execute when the window or frame finishes loading.
  • onUnload  Specifies JavaScript code to execute when the document in the window or frame is exited.

Independent Functions, Operators, Variables, and Literals

Independent Functions

  • escape(character)  Returns a string containing the ASCII encoding of character in the form %xx where xx is the numeric encoding of the character. [C|2|3|I]
  • eval(expression)  Returns the result of evaluating expression where expression is an arithmetic expression. [C|2|3|I]
  • isNaN(value)  Evaluates value to see if it is NaN. Returns a boolean value. [C|2|3|I] [On Unix platforms, Not2]
  • parseFloat(string)  Converts string to a floating-point number and returns the value. It continues to convert until it hits a non-numeric character and then returns the result. If the first character cannot be converted to a number the function returns "NaN" (zero on Windows platforms). [C|2|3|I]
  • parseInt(string,base)  Converts string to an integer of base base and returns the value. It continues to convert until it hits a non-numeric character and then returns the result. If the first character cannot be converted to a number, the function returns "NaN" (zero on Windows platforms). [C|2|3|I]
  • taint(propertyName)  Adds tainting to propertyName. [C|3]
  • toString()  This is a method of all objects. It returns the object as a string or returns "[object type]" if no string representation exists for the object. [C|2|3]
  • unescape(string)  Returns a character based on the ASCII encoding contained in string. The ASCII encoding should take the form "%integer" or "hexadecimalValue". [C|2|3|I]
  • untaint(propertyName)  Removes tainting from propertyName. [C|3]

Operators

  • Assignment Operators  Table B.1 shows the assignment operators in JavaScript. [C|2|3|I]

Table B.1. Assignment operators.

OperatorDescription
=Assigns value of right operand to the left operand
+= Adds the left and right operands and assigns the result to the left operand
-= Subtracts the right operand from the left operand and assigns the result to the left operand
*= Multiplies the two operands and assigns the result to the left operand
/= Divides the left operand by the right operand and assigns the value to the left operand
%= Divides the left operand by the right operand and assigns the remainder to the left operand

  • Arithmetic Operators  Table B.2 shows the arithmetic operators in JavaScript. [C|2|3|I]

Table B.2. Arithmetic operators.

OperatorDescription
+Adds the left and right operands
-Subtracts the right operand from the left operand
*Multiplies the two operands
/Divides the left operand by the right operand
%Divides the left operand by the right operand and evaluates to the remainder
++ Increments the operand by one (can be used before or after the operand)
-- Decreases the operand by one (can be used before or after the operand)
-Changes the sign of the operand

  • Bitwise Operators  Bitwise operators deal with their operands as binary numbers but return JavaScript numerical value (see Table B.3). [C|2|3|I]

Table B.3. Bitwise operators in JavaScript.

OperatorDescription
AND (or &) Converts operands to integers with 32 bits, pairs the corresponding bits and returns one for each pair of ones. Returns zero for any other combination.
OR (or |) Converts operands to integers with 32 bits, pairs the corresponding bits and returns one for each pair where one of the two bits is one. Returns zero if both bits are zero.
XOR (or ^) Converts operands to integer with 32 bits, pairs the corresponding bits and returns one for each pair where only one bit is one. Returns zero for any other combination.
<< Converts the left operand to an integer with 32 bits and shifts bits to the left the number of bits indicated by the right operand-bits shifted off to the left are discarded and zeros are shifted in from the right.
>> Converts the left operand to an integer with 32 bits and shifts bits to the right the number of bits indicated by the right operand-bits shifted off to the right are discarded and copies of the leftmost bit are shifted in from the left.

  • Logical Operators  Table B.4 shows the logical operators in JavaScript. [C|2|3|I]

Table B.4. Logical operators.

OperatorDescription
&& Logical "and"-returns true when both operands are true, otherwise it returns false.
|| Logical "or"-returns true if either operand is true. It only returns false when both operands are false.
!Logical "not"-returns true if the operand is false and false if the operand is true. This is a unary operator and precedes the operand.

  • Comparison Operators  Table B.5 shows the comparison Operators in JavaScript. [C|2|3|I]

Table B.5. Logical (comparison) operators.

OperatorDescription
== Returns true if the operands are equal
!= Returns true if the operands are not equal
> Returns true if the left operand is greater than the right operand
< Returns true if the left operand is less than the right operand
>= Returns true if the left operand is greater than or equal to the right operand
<= Returns true if the left operand is less than or equal to the right operand

  • Conditional Operators  Conditional expressions take one form:
    (condition) ? val1 : val2
    If condition is true, the expression evaluates to val1, otherwise it evaluates to val2. [C|2|3|I]
  • String Operators  The concatenation operators (+) is one of two string operators. It evaluates to a string combining the left and right operands. The concatenation assignment operator (+=) is also available. [C|2|3|I]
  • The typeof Operator  The typeof operator returns the type of its single operand. Possible types are object, string, number, boolean, function, and undefined. [C|3|I]
  • The void Operator  The void operator takes an expression as an operand but returns no value. [C|3]
  • Operator Precedence  JavaScript applies the rules of operator precedence as follows (from lowest to highest precedence):

comma (,)
assignment operators (= += -= *= /= %=)
conditional (? :)
logical or (||)
logical and (&&)
bitwise or (|)
bitwise xor (^)
bitwise and (&)
equality (== !=)
relational (< <= > >=)
shift (<< >> >>>)
addition/subtraction (+ -)
multiply/divide/modulus (* / %)
negation/increment (! - ++ --)
call, member (() [])

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The anchor Object [C|2|3|I]

The applet Object [C|3]

The area Object [C|3]

The Array Object [C|3|I]

The button Object [C|2|3|I]

The checkbox Object [c|2|3|I]

The combo Object [C|I]

The Date Object [C|2|3|I]

The document Object [C|2|3|I]

The FileUpload Object [C|3]

The form Object [C|2|3|I]

The frame Object [C|2|3|I]

The Function Object [C|3]

The hidden Object [C|2|3|I]

The history Object [C|2|3|I]

The Image Object [C|3]

The link Object [C|2|3|I]

The location Object [C|2|3|I]

The Math Object [C|2|3|I]

The mimeType Object [C|3]

The navigator Object [C|2|3|I]

The Option Object [C|3]

The password Object [C|2|3|I]

The plugin Object

The radio Object [C|2|3|I]

The reset Object [C|2|3|I]

The select Object [C|2|3]

The String Object [C|2|3|I]

The submit Object [C|2|3|I]

The text Object [C|2|3|I]

The textarea Object [C|2|3|I]

The window Object [C|2|3|I]

Independent Functions, Operators, Variables, and Literals

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