JavaScript Language Reference
-
JavaScript Language Reference
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.
See the anchors property of the document object.
The button object reflects a push button from an HTML form in JavaScript.
- name A string value containing the name of the button element.
- value A string value containing the value
of the button element.
- click() Emulates the action of
clicking on the button.
- onClick Specifies JavaScript code to
execute when the button is clicked.
The checkbox object makes a checkbox from an HTML form available in JavaScript.
- 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).
- name A string value containing the name
of the checkbox element.
- value A string value containing the value
of the checkbox element.
- click() Emulates the action of clicking on
the checkbox.
- onClick Specifies JavaScript code to
execute when the checkbox is clicked.
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 later two options represent integer values.
If no dateInfo is specified, the new object will represent the current date and
time.
- 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 1 January 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 of the week for
the current Date object as a two-digit integer representing the year less 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
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.
The document object reflects attributes of an HTML document in JavaScript.
- 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.
- bgColor The color of the document's
background.
- cookie A string value containing cookie
values for the current document.
- 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.
- 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.
- 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.
- vlinkColor The color of followed links as a
string or a hexadecimal triplet.
- clear() Clears the document window.
- 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.
- submit() Submits the form.
- 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.
- 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.
- parent A string indicating the name of
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.
- alert(message)
Displays message in a dialog box.
- 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.
- 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 is 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)
The hidden object reflects a hidden field from an HTML form in JavaScript.
- name A string value containing the name of the hidden element.
- value A string value containing the value of hidden text element.
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.
- length An integer representing the
number of items on the history list.
- back() Goes back to the previous
document in the history list.
- forward() Goes forward to the next
document in the history list.
- 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.
The link object reflects a hypertext link in the body of a document.
- target A string value containing the name
of the window or frame specified in the TARGET attribute.
- onClick Specifies JavaScript code to
execute when the link is clicked.
- onMouseOver Specifies JavaScript code
to execute when the mouse is over the hypertext link
The location object reflects information about the current URL.
- 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).
The Math object provides properties and methods for advanced mathematical
calculations.
- 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).
- PI The value of PI[md]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).
- abs(number) Returns the absolute value
of number. The absolute value is the value of a number with it's sign ignored so
abs(4) and abs(-4) both return 4
- acos(number)
Returns the arc cosine of number in radians.
- asin(number)
Returns the arc sine of number in radians.
- atan(number)
Returns the arc tangent of number in radians.
- ceil(number)
Returns the next integer greater than number[md]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[md]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 (at press time, this method only was available on UNIX versions of
Navigator 2.0).
- round(number)
Returns the closest integer to number[md]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.
- 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)".
- 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)
The password object reflects a password text field from an HTML form in JavaScript.
- defaultValue A string value containing
the default value of the password element (i.e. the value of the VALUE attribute).
- name A string value containing the name
of the password element.
- value A string value containing the value
of the password element.
- 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.
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.
- 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).
- length An integer value indicating the
number of radio buttons in the set.
- 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).
- click() Emulates the action of clicking on
a radio button.
- onClick Specifies JavaScript code to
execute when a radio button is clicked.
The reset object reflects a reset button from an HTML form in JavaScript.
- name A string value containing the name
of the reset element.
- value A string value containing the value
of the reset element.
- click() Emulates the action of clicking on
the reset button.
- onClick Specifies JavaScript code to
execute when the reset button is clicked.
The select object reflects a selection list from an HTML form in JavaScript.
- 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 it's 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.
|
options
|
A string value containing the full HTML code for 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.
- 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 provides properties and methods for working with string literals and
variables.
- length An integer value containing the
length of the string expressed as the number of characters in the string.
- 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.
- fontSize(size)
Returns a string containing the value of the string object surrounded by a FONTSIZE
container tag with the size set to size.
- indexOf(findString,startingIndex) Returns
the index of the first occurrence of findString, starting the search at
startingIndex where startingIndex is optional[md]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.
- 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 lower case.
- toUpperCase() Returns a string
containing the value of the string object with all character converted to upper case.
The submit object reflects a submit button from an HTML form in JavaScript.
- name A string value containing the name
of the submit button element.
- value A string value containing the value
of the submit button element.
- click() Emulates the action of clicking on
the submit button.
- onClick Specifies JavaScript code to
execute when the submit button is clicked.
The text object reflects a text field from an HTML form in JavaScript.
- defaultValue A string value containing
the default value of the text element (i.e. the value of the VALUE attribute).
- name A string value containing the name
of the text element.
- value A string value containing the value
of the text element.
- 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.
- 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 reflects a multi-line text field from an HTML form in JavaScript.
- defaultValue A string value containing
the default value of the textarea element (i.e. the value of the VALUE attribute).
- name A string value containing the name
of the textarea element.
- value A string value containing the value
of the textarea element.
- 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.
- 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 is the top-level object for each window or frame and is the parent
object for the document, location and history objects.
- 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.
- name A string value containing the name
of the window or frame.
- 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[md]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.
- alert(message)
Displays message in a dialog box.
- 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.
- 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)
- 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
- escape(character) Returns a string
containing the ASCII encoding of character in the form %xx where
xx is the numeric encoding of the character.
- eval(expression) Returns the result of
evaluating expression where expression is an arithmetic
expression.
- isNaN(value)
Evaluates value to see if it is NaN. Returns a boolean value. This function is only
available on UNIX platforms where certain functions return NaN if their argument is not
a number.
- 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).
- 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).
- unescape(string)
Returns a character based on the ASCII encoding contained in string. The ASCII
encoding should take the form "%integer" or
"hexadecimalValue".
- Assignment Operators Table B.1.
Assignment operators in JavaScript
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 |
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).
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[md]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[md]bits shifted off to the right are discarded and zeros are
shifted in from the left
|
>>
|
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[md]bits shifted off to the right are discarded and
copies of the leftmost bit are shifted in from the left |
Table B.4. Logical operators.
Operator
|
Description
|
&&
|
Logical "and"[md]returns true when both operands are true, otherwise it returns
false
|
||
|
Logical "or"[md]returns true if either operand is true. It only returns false when
both operands are false
|
!
|
Logical "not"[md]returns true if the operand is false and false if the operand
is true. This is a unary operator and precedes the operand. |
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 |
- Conditional Operators Conditional
expressions take one form:
(condition) ? val1 :
val2
If condition is true, the expression evaluates to val1,
otherwise it evaluates to val2.
- 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.
- 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 (() [])