JavaScript HTML DOM - Changing HTML
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 Sep 28 2014 01:12:28 GMT+0500 (West Asia Standard Time)
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>
<html>
<body>
<script>
document.write(Date());
</script>
</body>
</html>
 | 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>
<body>
<p id="p1">Hello World!</p>
<script>
document.getElementById("p1").innerHTML = "New text!";
</script>
</body>
</html>
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>
<html>
<body>
<h1 id="header">Old Header</h1>
<script>
var element = document.getElementById("header");
element.innerHTML = "New Header";
</script>
</body>
</html>
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>
<html>
<body>
<img id="myImage" src="smiley.gif">
<script>
document.getElementById("myImage").src = "landscape.jpg";
</script>
</body>
</html>
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"
