Date object

Changed in Navigator 3.0

Lets you work with dates and times.

Syntax

To create a Date object:

1. dateObjectName = new Date()
2. dateObjectName = new Date("month day, year hours:minutes:seconds")
3. dateObjectName = new Date(year, month, day)
4. dateObjectName = new Date(year, month, day, hours, minutes, seconds)
dateObjectName is either the name of a new object or a property of an existing object.
month, day, year, hours, minutes, and seconds are string values for form 2 of the syntax. For forms 3 and 4, they are integer values.

To use Date methods:

dateObjectName.methodName(parameters)
dateObjectName is either the name of an existing Date object or a property of an existing object..
methodName is one of the methods listed below.

Exceptions: The Date object's parse and UTC methods are static methods that you use as follows:

Date.UTC(parameters)
Date.parse(parameters)

Property of

  • None.

    Description

    The Date object is a built-in JavaScript object.

    Form 1 of the syntax creates today's date and time. If you omit hours, minutes, or seconds from form 2 or 4 of the syntax, the value will be set to zero.

    The way JavaScript handles dates is very similar to the way Java handles dates: both languages have many of the same date methods, and both store dates internally as the number of milliseconds since January 1, 1970 00:00:00. Dates prior to 1970 are not allowed.

    Properties

  • None.

    Methods

  • getDate
  • getDay
  • getHours
  • getMinutes
  • getMonth
  • getSeconds
  • getTime
  • getTimezoneOffset
  • getYear
  • parse
  • setDate
  • setHours
  • setMinutes
  • setMonth
  • setSeconds
  • setTime
  • setYear
  • toGMTString
  • toLocaleString
  • UTC

    Event handlers

  • None. Built-in objects do not have event handlers.

    Examples

    today = new Date() birthday = new Date("December 17, 1995 03:24:00") birthday = new Date(95,12,17) birthday = new Date(95,12,17,3,24,0)

    defaultChecked property

    A Boolean value indicating the default selection state of a checkbox or radio button.

    Syntax

    1. checkboxName.defaultChecked
    2. radioName[index].defaultChecked
    

    checkboxName is either the value of the NAME attribute of a checkbox object or an element in the elements array.
    radioName is the value of the NAME attribute of a radio object.
    index is an integer representing a radio button in a radio object.

    Property of

    checkbox, radio

    Description

    If an checkbox or radio button is selected by default, the value of the defaultChecked property is true; otherwise, it is false. defaultChecked initially reflects whether the CHECKED attribute is used within an <INPUT> tag; however, setting defaultChecked overrides the CHECKED attribute.

    You can set the defaultChecked property at any time. The display of the checkbox or radio button does not update when you set the defaultChecked property, only when you set the checked property.

    Examples

    The following example resets an array of radio buttons called musicType on the musicForm form to the default selection state.

    function radioResetter() {
       var i=""
       for (i in document.musicForm.musicType) {
          if (document.musicForm.musicType[i].defaultChecked==true) {
             document.musicForm.musicType[i].checked=true
          }
       }
    }
    

    See also

  • checked property

    defaultSelected property

    Changed in Navigator 3.0

    A Boolean value indicating the default selection state of an option in a select object.

    Syntax

    selectName.options[index].defaultSelected

    selectName is either the value of the NAME attribute of a select object or an element in the elements array.
    index is an integer representing an option in a select object.

    Property of

    options array

    Description

    If an option in a select object is selected by default, the value of the defaultSelected property is true; otherwise, it is false. defaultSelected initially reflects whether the SELECTED attribute is used within an <OPTION> tag; however, setting defaultSelected overrides the SELECTED attribute.

    You can set the defaultSelected property at any time. The display of the select object does not update when you set the defaultSelected property, only when you set the selected or selectedIndex properties.

    A select object created without the MULTIPLE attribute can have only one option selected by default. When you set defaultSelected in such an object, any previous default selections, including defaults set with the SELECTED attribute, are cleared. If you set defaultSelected in a select object created with the MULTIPLE attribute, previous default selections are not affected.

    Examples

    In the following example, the restoreDefault() function returns the musicType select object to its default state. The for loop uses the options array to evaluate every option in the select object. The if statement sets the selected property if defaultSelected is true.

    function restoreDefault() {
       for (var i = 0; i < document.musicForm.musicType.length; i++) {
          if (document.musicForm.musicType.options[i].defaultSelected == true) {
             document.musicForm.musicType.options[i].selected=true
          }
       }
    }
    
    The previous example assumes that the select object is similar to the following:
    <SELECT NAME="musicType"> 
       <OPTION SELECTED> R&B
       <OPTION> Jazz
       <OPTION> Blues
       <OPTION> New Age
    </SELECT>
    

    See also

  • index, selected, selectedIndex properties

    defaultStatus property

    The default message displayed in the status bar at the bottom of the window.

    Syntax

    windowReference.defaultStatus

    windowReference is a valid way of referring to a window, as described in the window object.

    Property of

    window

    Description

    The defaultStatus message appears when nothing else is in the status bar. Do not confuse the defaultStatus property with the status property. The status property reflects a priority or transient message in the status bar, such as the message that appears when a mouseOver event occurs over an anchor.

    You can set the defaultStatus property at any time. You must return true if you want to set the defaultStatus property in the onMouseOver event handler.

    Examples

    In the following example, the statusSetter() function sets both the status and defaultStatus properties in an onMouseOver event handler:

    function statusSetter() {
       window.defaultStatus = "Click the link for the Netscape home page"
       window.status = "Netscape home page"
    }
    
    <A HREF="http://www.netscape.com"
       onMouseOver = "statusSetter(); return true">Netscape</A>
    
    In the previous example, notice that the onMouseOver event handler returns a value of true. You must return true to set status or defaultStatus in an event handler.

    See also

  • status property

    defaultValue property

    A string indicating the default value of a password, text, or textarea object.

    Syntax

    1. passwordName.defaultValue
    2. textName.defaultValue
    3. textareaName.defaultValue
    

    passwordName is either the value of the NAME attribute of a password object or an element in the elements array.
    textName is either the value of the NAME attribute of a text object or an element in the elements array.
    textareaName is either the value of the NAME attribute of a textarea object or an element in the elements array.

    Property of

    password, text, textarea

    Description

    The initial value of defaultValue differs for each object:

  • For text objects, it initially reflects the value of the VALUE attribute.
  • For textarea objects, it initially reflects the value specified between the <TEXTAREA> and </TEXTAREA> tags.
  • For password objects, it initially is null (for security reasons), regardless of the value of the VALUE attribute.

    Setting defaultValue programatically overrides the initial setting. If you programatically set defaultValue for the password object and then evaluate it, JavaScript returns the current value.

    You can set the defaultValue property at any time. The display of the related object does not update when you set the defaultValue property, only when you set the value property.

    Examples

    The following function evaluates the defaultValue property of objects on the surfCity form and displays the values in the msgWindow window:

    function defaultGetter() {
       msgWindow=window.open("")
       msgWindow.document.write("hidden.defaultValue is " +
          document.surfCity.hiddenObj.defaultValue + "<BR>")
       msgWindow.document.write("password.defaultValue is " +
          document.surfCity.passwordObj.defaultValue + "<BR>")
       msgWindow.document.write("text.defaultValue is " +
          document.surfCity.textObj.defaultValue + "<BR>")
       msgWindow.document.write("textarea.defaultValue is " +
          document.surfCity.textareaObj.defaultValue + "<BR>")
       msgWindow.document.close()
    }
    

    See also

  • value property

    document object

    Changed in Navigator 3.0

    Contains information on the current document, and provides methods for displaying HTML output to the user.

    Syntax

    To define a document object, use standard HTML syntax:

    <BODY
       BACKGROUND="backgroundImage"
       BGCOLOR="backgroundColor"
       TEXT="foregroundColor"
       LINK="unfollowedLinkColor"
       ALINK="activatedLinkColor"
       VLINK="followedLinkColor"
       [onLoad="handlerText"]
       [onUnload="handlerText"]>
    </BODY>
    
    BACKGROUND specifies an image that fills the background of the document.
    BGCOLOR, TEXT, LINK, ALINK, and VLINK are color specifications expressed as a hexadecimal RGB triplet (in the format "rrggbb" or "#rrggbb") or as one of the string literals listed in Color Values.

    To use a document object's properties and methods:

    1. document.propertyName
    2. document.methodName(parameters)
    
    propertyName is one of the properties listed below.
    methodName is one of the methods listed below.

    Property of

  • window

    Description

    An HTML document consists of a <HEAD> and <BODY> tag. The <HEAD> includes information on the document's title and base (the absolute URL base to be used for relative URL links in the document). The <BODY> tag encloses the body of a document, which is defined by the current URL. The entire body of the document (all other HTML elements for the document) goes within the <BODY> tag.

    You can load a new document by using the location object.

    You can reference the anchors, forms, and links of a document by using the anchors, forms, and links arrays. These arrays contain an entry for each anchor, form, or link in a document.

    Properties

  • alinkColor reflects the ALINK attribute
  • anchors is an array reflecting all the anchors in a document
  • bgColor reflects the BGCOLOR attribute
  • cookie specifies a cookie
  • fgColor reflects the TEXT attribute
  • forms is an array reflecting all the forms in a document
  • lastModified reflects the date a document was last modified
  • linkColor reflects the LINK attribute
  • links is an array reflecting all the links in a document
  • referrer reflects the URL of the calling document
  • title reflects the contents of the <TITLE> tag
  • URL reflects the complete URL of a document
  • vlinkColor reflects the VLINK attribute

    The following objects are also properties of the document object:

  • anchor
  • form
  • history
  • link

    Methods

  • close
  • open
  • write
  • writeln

    Event handlers

  • None. The onLoad and onUnload event handlers are specified in the <BODY> tag but are actually event handlers for the window object.

    Examples

    The following example creates two frames, each with one document. The document in the first frame contains links to anchors in the document of the second frame. Each document defines its colors.

    DOC0.HTML, which defines the frames, contains the following code:

    <HTML> <HEAD> <TITLE>Document object example</TITLE> </HEAD> <FRAMESET COLS="30%,70%"> <FRAME SRC="doc1.html" NAME="frame1"> <FRAME SRC="doc2.html" NAME="frame2"> </FRAMESET> </HTML>

    DOC1.HTML, which defines the content for the first frame, contains the following code:

    <HTML> <SCRIPT> </SCRIPT> <BODY BGCOLOR="antiquewhite" TEXT="darkviolet" LINK="fuchsia" ALINK="forestgreen" VLINK="navy"> <P><B>Some links</B> <LI><A HREF="doc2.html#numbers" TARGET="frame2">Numbers</A> <LI><A HREF="doc2.html#colors" TARGET="frame2">Colors</A> <LI><A HREF="doc2.html#musicTypes" TARGET="frame2">Music types</A> <LI><A HREF="doc2.html#countries" TARGET="frame2">Countries</A> </BODY> </HTML>

    DOC2.HTML, which defines the content for the second frame, contains the following code:

    <HTML> <SCRIPT> </SCRIPT> <BODY BGCOLOR="oldlace" onLoad="alert('Hello, World.')" TEXT="navy"> <P><A NAME="numbers"><B>Some numbers</B></A> <LI>one <LI>two <LI>three <LI>four <LI>five <LI>six <LI>seven <LI>eight <LI>nine <P><A NAME="colors"><B>Some colors</B></A> <LI>red <LI>orange <LI>yellow <LI>green <LI>blue <LI>purple <LI>brown <LI>black <P><A NAME="musicTypes"><B>Some music types</B></A> <LI>R&B <LI>Jazz <LI>Soul <LI>Reggae <LI>Rock <LI>Country <LI>Classical <LI>Opera <P><A NAME="countries"><B>Some countries</B></A> <LI>Afghanistan <LI>Brazil <LI>Canada <LI>Finland <LI>India <LI>Italy <LI>Japan <LI>Kenya <LI>Mexico <LI>Nigeria </BODY> </HTML>

    See also

  • frame and window objects

    E property

    Euler's constant and the base of natural logarithms, approximately 2.718.

    Syntax

    Math.E

    Property of

    Math

    Description

    Because E is a constant, it is a read-only property of Math.

    Examples

    The following example displays Euler's constant:

    document.write("Euler's constant is " + Math.E)

    See also

  • LN2, LN10, LOG2E, LOG10E, PI, SQRT1_2, SQRT2 properties

    elements array

    An array of objects corresponding to form elements (such as checkbox, radio, and text objects) in source order.

    Syntax

    1. formName.elements[index]
    2. formName.elements.length
    

    formName is either the name of a form or an element in the forms array.
    index is an integer representing an object on a form.

    Property of

  • form

    Description

    You can reference a form's elements in your code by using the elements array. This array contains an entry for each object (button, checkbox, hidden, password, radio, reset, select, submit, text, or textarea object) in a form in source order. For example, if a form has a text field and two checkboxes, these elements are reflected as formName.elements[0], formName.elements[1], and formName.elements[2].

    Although you can also reference a form's elements by using the element's name (from the NAME attribute), the elements array provides a way to reference form objects programatically without using their names. For example, if the first object on the userInfo form is the userName text object, you can evaluate it in either of the following ways:

    userInfo.userName.value
    userInfo.elements[0].value
    

    To obtain the number of elements on a form, use the length property: formName.elements.length. Each radio button in a radio object appears as a separate element in the elements array.

    Elements in the elements array are read-only. For example, the statement formName.elements[0]="music" has no effect.

    The value of each element in the elements array is the full HTML statement for the object.

    Properties

  • length reflects the number of elements on a form

    Examples

    See the examples for the name property.

    See also

  • form object

    elements property

    An array of objects corresponding to form elements (such as checkbox, radio, and text objects) in source order. See elements array.


    encoding property

    A string specifying the MIME encoding of the form.

    Syntax

    formName.encoding

    formName is either the name of a form or an element in the forms array.

    Property of

    form

    Description

    The encoding property initially reflects the ENCTYPE attribute of the <FORM> tag; however, setting encoding overrides the ENCTYPE attribute.

    You can set the encoding property at any time.

    Certain values of the encoding property may require specific values for other form properties. See RFC 1867 for more information.

    Examples

    The following function returns the value of the musicForm encoding property:

    function getEncoding() {
       return document.musicForm.encoding
    }
    

    See also

  • action, method, target properties

    escape function

    Returns the ASCII encoding of an argument in the ISO Latin-1 character set.

    Syntax

    escape("string")

    string is a non-alphanumeric string in the ISO Latin-1 character set, or a property of an existing object.

    Description

    The escape function is not a method associated with any object, but is part of the language itself.

    The value returned by the escape function is a string of the form "%xx", where xx is the ASCII encoding of a character in the argument. If you pass the escape function an alphanumeric character, the escape function returns the same character.

    Examples

    The following example returns "%26"

    escape("&")
    

    The following example returns "%21%23"

    escape("!#")
    

    See also

  • unescape function

    eval function

    The eval function evaluates a string and returns a value.

    Syntax

    eval(string)
    string is any string representing a JavaScript expression, statement, or sequence of statements. The expression can include variables and properties of existing objects.

    Description

    The eval function is a built-in JavaScript function. It is not a method associated with any object, but is part of the language itself.

    The argument of the eval function is a string. Do not call eval to evaluate an arithmetic expression. JavaScript evaluates arithmetic expressions automatically. If the argument represents an expression, eval evaluates the expression. If the argument represents one or more JavaScript statements, eval performs the statements.

    If you construct an arithmetic expression as a string, you can use eval to evaluate it at a later time. For example, suppose you have a variable x. You can postpone evaluation of an expression involving x by assigning the string value of the expression, say "3 * x + 2", to a variable, and then calling eval at a later point in your script.

    Examples

    Example 1. Both of the write statements below display 42. The first evaluates the string "x + y + 1", and the second evaluates the string "42".

    var x = 2
    var y = 39
    var z = "42"
    document.write(eval("x + y + 1"), "<BR>") 
    document.write(eval(z), "<BR>")
    

    Example 2. In the following example, the getFieldName(n) function returns the name of the nth form element as a string. The first statement assigns the string value of the third form element to the variable field. The second statement uses eval to display the value of the form element.

    var field = getFieldName(3) 
    document.write("The field named ", field, " has value of ", eval(field + ".value"))
    

    Example 3. The following example uses eval to evaluate the string str. This string consists of JavaScript statements that opens an alert dialog box and assigns z a value of 42 if x is five, and assigns zero to z otherwise. When the second statement is executed, eval will cause these statements to be performed, and it will also evaluate the set of statements and return the value that is assigned to z.

    var str = "if (x == 5) {alert('z is 42'); z = 42;} else z = 0; "
    document.write("<P>z is ", eval(str))
    

    Example 4. In the following example, the setValue() function uses eval to assign the value of the variable newValue to the text field textObject.

    function setValue (textObject, newValue) {
      eval ("document.forms[0]." + textObject + ".value") = newValue
    }
    

    exp method

    Returns enumber, where number is the argument, and e is Euler's constant, the base of the natural logarithms.

    Syntax

    Math.exp(number)
    number is any numeric expression or a property of an existing object.

    Method of

    Math

    Examples

    //Displays the value 2.718281828459045
    document.write("The value of e<SUP>1</SUP> is " + Math.exp(1))
    

    See also

  • log, pow methods