Document Object Model

1. Document Object
2. Properties of document object
3. Methods of document object
4. Example of document object

The document object represents the whole html document.

When html document is loaded in the browser, it becomes a document object. It is the root element that represents the html document. It has properties and methods. By the help of document object, we can add dynamic content to our web page.

As mentioned earlier, it is the object of window. So

    

1. document  

                   Is same as

      

1. document  

                     According to W3C - "The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document."

                          

Properties of document object

Let's see the properties of document object that can be accessed and modified by the document object.

                       

Methods of document object

We can access and change the contents of document by its methods.

The important methods of document object are as follows:

Method	Description
write("string")	writes the given string on the doucment.
writeln("string")	writes the given string on the doucment with newline character at the end.
getElementById()	returns the element having the given id value.
getElementsByName()	returns all the elements having the given name value.
getElementsByTagName()	returns all the elements having the given tag name.
getElementsByClassName()	returns all the elements having the given class name.

                    

Accessing field value by document object

In this example, we are going to get the value of input text by user. Here, we are using document.form1.name.value to get the value of name field.

Here, document is the root element that represents the html documform1 is the name of the form.

name is the attribute name of the input text.

value is the property, that returns the value of the input text.

Let's see the simple example of document object that prints name with welcome message.

1. <script type="text/javascript">  
2. function printvalue(){  
3. var name=document.form1.name.value;  
4. alert("Welcome: "+name);  
5. }  
6. </script>  
7.   
8. <form name="form1">  
9. Enter Name:<input type="text" name="name"/>  
10. <input type="button" onclick="printvalue()" value="print name"/>  
11. </form>  

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Output of the above example

Enter Name: