DOM Elements

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

Finding HTML Elements #

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

To do so, you have to find the elements first. There are several 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

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.

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");

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.

Finding HTML Elements by CSS Selectors #

If you want to find all HTML elements that match 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.

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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