DOM Elements

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 CSS selectors
• Finding HTML elements by HTML object collections

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Finding HTML Element by Id

The easiest way to find an HTML element in the DOM, is by using the element id.
This example finds the element with id="intro":

Example

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

If the element is found, the method will return the element as an object (in myElement).
If the element is not found, myElement will contain null.

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Finding HTML Elements by Tag Name

This example finds all <p> elements:

Example

var x = document.getElementsByTagName("p");

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 getElementsByClassName().

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

Example

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

Finding elements by class name does not work in Internet Explorer 8 and earlier versions.

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Finding HTML Elements by CSS Selectors

If you want to find all HTML elements that matches a specified CSS selector (id, class names, types, attributes, values of attributes, etc), use the querySelectorAll() method.

This example returns a list of all <p> elements with class="intro".

Example

var x = document.querySelectorAll("p.intro");

The querySelectorAll() method does not work in Internet Explorer 8 and earlier versions.

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

The following HTML objects (and object collections) are also accessible:

• document.anchors
• document.body
• document.documentElement
• document.embeds
• document.forms
• document.head
• document.images
• document.links
• document.scripts
• document.title

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