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)
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 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 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 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 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 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 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 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 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 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 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 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 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 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 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.
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
AssignmentOperators Table
B.1 shows the assignment operators in JavaScript. [C|2|3|I]
Table B.1. Assignment operators.
Operator
Description
=
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
ArithmeticOperators Table
B.2 shows the arithmetic operators in JavaScript. [C|2|3|I]
Table B.2. Arithmetic operators.
Operator
Description
+
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.
Operator
Description
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.
LogicalOperators Table
B.4 shows the logical operators in JavaScript. [C|2|3|I]
Table B.4. Logical operators.
Operator
Description
&&
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.
ComparisonOperators Table
B.5 shows the comparison Operators in JavaScript. [C|2|3|I]
Table B.5. Logical (comparison) operators.
Operator
Description
==
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
ConditionalOperators 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]
StringOperators 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 (()[])
JavaScript Language Reference code practice
JavaScript Language Reference tutorial
JavaScript Language Reference syntax code on this is provided for your study purpose, it will guide you to know how create and design a website using html. use it to practice and train your self online
All the tutorials on this site are free, the codes are provided for you to practice, if you want to help to improve and maintain this work, you can donate to us on.
All the tutorials on this site are provided for free. You can copy and print the tutorials and code on this site, but you are not allowed to reproduce this information on another website. All rights reserverd 2012