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JavaScript HTML 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 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

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

Test Yourself with Exercises!

Exercise 1 »  Exercise 2 »  Exercise 3 »  Exercise 4 »  Exercise 5 »


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