DOCUMENT
OBJECT :
Every web page resides inside a
browser window which is considered as an object.
A Document object represents
the HTML document that is displayed in that window.
The Document object has various
properties that refer to other objects which allow access to and modification
of document content.
The way the document content is
accessed and modified is called the Document
Object Model, or DOM.
·
Window object: Top of the hierarchy. It is the outmost element of the object
hierarchy.
·
Document object: Each HTML document that gets loaded into a window becomes a
document object. The document contains the content of the page.
·
Form object: Everything enclosed in the <form>...</form> tags sets
the form object.
·
Form control elements: The form object contains all the elements defined for that object
such as text fields, buttons, radio buttons, and checkboxes.
It contains these
properties:
·
documentElement, body, title: references the <html>, <body> and <title> tags respectively.
·
lastModified, referrer, cookie, domain: information retrieved from the HTTP
response header.
·
form[], applets[], images[], embeds[], links[], anchors[]: Arrays containing the respective HTML
elements
The document object has the following
methods:
·
write(string), writeln(string): Write the specified
string to the current document. writeln() (write-line) writes a
newline after the string, while write() does not. clear(): Clear the document.
·
open(), close(): Open/close the document stream.
·
getElementById(), getElementsByName(), getElementsByTagName(): Select HTML element(s) by
id, name, or tag-name, respectively.
Example: The following example changes the content (the
innerHTML) of the <p> element with id="demo":
getElementById is a method, innerHTML
is a property.
<html>
<body>
<h1>My First
Page</h1>
<p
id="demo"></p>
<script>
document.getElementById("demo").innerHTML
= "Hello World!";
</script>
</body>
</html>
Output:
My First Page
Hello
World!
The
getElementById Method
The most common way to access
an HTML element is to use the id of the element.
In the example above the
getElementById method used id="demo" to find the element.
The innerHTML Property
The easiest way to get the
content of an element is by using the innerHTML property.
The innerHTML property is
useful for getting or replacing the content of HTML elements.
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