The HTML DOM allows JavaScript to change the content of HTML elements.
Changing the HTML Output Stream
JavaScript can create dynamic HTML content:
Date: Sun Nov 06 2016 19:23:35 GMT+0800 (中国标准时间)
In JavaScript, document.write() can be used to write directly to the HTML output stream:
Example
<!DOCTYPE html>
<html>
<body>
<script>
document.write(Date());
</script>
</body>
</html>
Try it Yourself »
Never use document.write() after the document is loaded. It will overwrite the document.
Changing HTML Content
The easiest way to modify the content of an HTML element is by using the innerHTML property.
To change the content of an HTML element, use this syntax:
document.getElementById(id).innerHTML = new HTML
This example changes the content of a <p> element:
Example
<html>
<body>
<p id="p1">Hello World!</p>
<script>
document.getElementById("p1").innerHTML = "New text!";
</script>
</body>
</html>
Try it Yourself »
This example changes the content of an <h1> element:
Example
<!DOCTYPE html>
<html>
<body>
<h1 id="header">Old Header</h1>
<script>
var element = document.getElementById("header");
element.innerHTML = "New Header";
</script>
</body>
</html>
Try it Yourself »
Example explained:
- The HTML document above contains an <h1> element with id="header"
- We use the HTML DOM to get the element with id="header"
- A JavaScript changes the content (innerHTML) of that element
Changing the Value of an Attribute
To change the value of an HTML attribute, use this syntax:
document.getElementById(id).attribute=new value
This example changes the value of the src attribute of an <img> element:
Example
<!DOCTYPE html>
<html>
<body>
<img id="myImage" src="smiley.gif">
<script>
document.getElementById("myImage").src = "landscape.jpg";
</script>
</body>
</html>
Try it Yourself »
Example explained:
- The HTML document above contains an <img> element with id="myImage"
- We use the HTML DOM to get the element with id="myImage"
- A JavaScript changes the src attribute of that element from "smiley.gif" to "landscape.jpg"
Test Yourself with Exercises!
Exercise 1 » Exercise 2 » Exercise 3 » Exercise 4 » Exercise 5 »