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JavaScript - The Legacy DOM

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This is the model which was introduced in early versions of JavaScript language. It is well supported by all browsers, but allows access only to certain key portions of documents, such as forms, form elements, and images.

This model provides several read-only properties, such as title, URL, and lastModified provide information about the document as a whole. Apart from that there are various methods provided by this model which can be used to set and get document property values.

Document Properties in Legacy DOM:

Here is the list of document properties which can be accessed using Legacy DOM:

PropertyDescription & Example
alinkColorDeprecated - A string that specifies the color of activated links.
Example: document.alinkColor
anchors[ ]An array of Anchor objects, one for each anchor that appears in the document
Example: document.anchors[0], document.anchors[1] and so on
applets[ ] An array of Applet objects, one for each applet that appears in the document
Example: document.applets[0], document.applets[1] and so on
bgColor Deprecated - A string that specifies the background color of the document.
Example: document.bgColor
cookieA string-valued property with special behavior that allows the cookies associated with this document to be queried and set.
Example: document.cookie
domainA string that specifies the Internet domain the document is from. Used for security purpose.
Example: document.domain
embeds[ ]An array of objects that represent data embedded in the document with the <embed> tag. A synonym for plugins[ ]. Some plugins and ActiveX controls can be controlled with JavaScript code.
Example: document.embeds[0], document.embeds[1] and so on
fgColorDeprecated - A string that specifies the default text color for the document
Example: document.fgColor
forms[ ]An array of Form objects, one for each HTML form that appears in the document.
Example: document.forms[0], document.forms[1] and so on
images[ ]An array of Image objects, one for each image that is embedded in the document with the HTML <img> tag.
Example: document.images[0], document.images[1] and so on
lastModified A read-only string that specifies the date of the most recent change to the document
Example: document.lastModified
linkColorDeprecated - A string that specifies the color of unvisited links
Example: document.linkColor
links[ ]links[ ]
Example: document.links[0], document.links[1] and so on
location The URL of the document. Deprecated in favor of the URL property.
Example: document.location
plugins[ ]A synonym for the embeds[ ]
Example: document.plugins[0], document.plugins[1] and so on
referrer A read-only string that contains the URL of the document, if any, from which the current document was linked.
Example: document.referrer
titleThe text contents of the <title> tag.
Example: document.title
URLA read-only string that specifies the URL of the document.
Example: document.URL
vlinkColorDeprecated - A string that specifies the color of visited links.
Example: document.vlinkColor

Document Methods in Legacy DOM:

Here is the list of methods supported by Legacy DOM:

PropertyDescription & Example
clear( )Deprecated - Erases the contents of the document and returns nothing.
Example: document.clear( )
close( ) Closes a document stream opened with the open( ) method and returns nothing.
Example: document.close( )
open( )Deletes existing document content and opens a stream to which new document contents may be written. Returns nothing.
Example: document.open( )
write( value, ...)Inserts the specified string or strings into the document currently being parsed or appends to document opened with open( ). Returns nothing.
Example: document.write( value, ...)
writeln( value, ...) Identical to write( ), except that it appends a newline character to the output. Returns nothing.
Example: document.writeln( value, ...)

Example:

We can locate any HTML element with-in any HTML document using HTML DOM. For instance, if a web document contains a form element then using JavaScript we can refer to it as document.forms[0]. If your Web document includes two form elements the first form is referred to as document.forms[0] and the second document.forms[1].

Using the hierarchy and properties given above, we can access first form element using document.forms[0].elements[0] and so on.

Here is an example to access document properties using Legacy DOM method:

<html>
<head>
<title> Document Title </title>
<script type="text/javascript">
<!--
function myFunc()
{
   var ret = document.title;
   alert("Document Title : " + ret );

   var ret = document.URL;
   alert("Document URL : " + ret );

   var ret = document.forms[0];
   alert("Document First Form : " + ret );

   var ret = document.forms[0].elements[1];
   alert("Second element : " + ret );

}
//-->
</script>
</head>
<body>
<h1 id="title">This is main title</h1>
<p>Click the following to see the result:</p>

<form name="FirstForm">
<input type="button" value="Click Me" onclick="myFunc();" />
<input type="button" value="Cancel">
</form>

<form name="SecondForm">
<input type="button" value="Don't ClickMe"/>
</form>

</body>
</html>

NOTE: This example returns objects for forms and elements etc and we would have to access their values by using those object properties which are not discussed in this tutorial.

To understand it in better way you can Try it yourself.


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