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.

The anchor Object

See the anchors property of the document object.

The button Object

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

Properties

• name A string value containing the name of the button element.
  
  
• value A string value containing the value of the button element.
  
  

Methods

• click() Emulates the action of clicking on the button.
  
  

Event Handlers

• onClick Specifies JavaScript code to execute when the button is clicked.
  
  

The checkbox Object

The checkbox object makes a checkbox from 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).
  
  
• name A string value containing the name of the checkbox element.
  
  
• value A string value containing the value of the checkbox element.
  
  

Methods

• click() Emulates the action of clicking on the checkbox.
  
  

Event Handlers

• onClick Specifies JavaScript code to execute when the checkbox is clicked.
  
  

The Date Object

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.

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 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

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.
  
  
• 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.
  
  

Methods

• 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

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

• submit() Submits the form.
  
  

Event Handlers

• 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

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.
  
  
• 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.
  
  

Methods

• 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)

• clearTimeout(name) Cancels the time out with the name name.
  
  

The hidden Object

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.
  
  
• value A string value containing the value of hidden text element.
  
  

The history 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.

Properties

• length An integer representing the number of items on the history list.
  
  

Methods

• 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

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

Properties

• target A string value containing the name of the window or frame specified in the TARGET attribute.
  
  

Event Handlers

• 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

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).
  
  

The Math Object

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).
  
  
• 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 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—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 (at press time, this method only was available on UNIX versions of Navigator 2.0).
  
  
• 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

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)".
  
  
• 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

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).
  
  
• 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.
  
  

The radio Object

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).
  
  
• 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).
  
  

Methods

• click() Emulates the action of clicking on a radio button.
  
  

Event Handlers

• onClick Specifies JavaScript code to execute when a radio button is clicked.
  
  

The reset Object

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

Properties

• 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.
  
  

Event Handlers

• onClick Specifies JavaScript code to execute when the reset button is clicked.
  
  

The select Object

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 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.
  
  

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

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.
  
  

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.
  
  
• 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—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

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

Properties

• name A string value containing the name of the submit button element.
  
  
• value A string value containing the value of the submit button element.
  
  

Methods

• click() Emulates the action of clicking on the submit button.
  
  

Event Handlers

• onClick Specifies JavaScript code to execute when the submit button is clicked.
  
  

The text Object

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).
  
  
• name A string value containing the name of the text element.
  
  
• 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

The textarea object reflects a multi-line 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).
  
  
• name A string value containing the name of the textarea element.
  
  
• 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.