JavaScript HTML DOM Elements

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This page teaches you how to find and access HTML elements in an HTML page.

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Finding HTML Elements

Often, with JavaScript, you want to manipulate HTML elements.

To do so, you have to find the elements first. There are a couple of ways to do this:

• Finding HTML elements by id
• Finding HTML elements by tag name
• Finding HTML elements by class name
• Finding HTML elements by HTML object collections

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Finding HTML Elements by Id

The easiest way to find HTML elements in the DOM, is by using the element id.

This example finds the element with id="intro":

Example

var x = document.getElementById("intro");

If the element is found, the method will return the element as an object (in x).

If the element is not found, x will contain null.

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Finding HTML Elements by Tag Name

This example finds the element with id="main", and then finds all <p> elements inside "main":

Example

var x = document.getElementById("main");
var y = x.getElementsByTagName("p");

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Finding HTML Elements by Class Name

If you want to find all HTML elements with the same class name. Use this method:

document.getElementsByClassName("intro");

The example above returns a list of all elements with class="intro".

	Finding elements by class name does not work in Internet Explorer 5,6,7, and 8.

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Finding HTML Elements by HTML Object Collections

This example finds the form element with id="frm1", in the forms collection, and displays all element values:

Example

var x = document.getElementById("frm1");
var text = "";
var i;
for (i = 0; i < x.length; i++) {
    text += x.elements[i].value + "<br>";
}
document.getElementById("demo").innerHTML = text;