JS Tutorial
JS Version
JS Objects
JS Function
JS Classes
JS Async
JS HTML DOM
JS Browser BOM
JS Web API
JS AJAX
JS JSON
JS vs JQUERY
JS Graphics
DOM Intro
The HTML DOM enables JavaScript to change the content of HTML elements.
Changing HTML Content
The easy way to modify the content of an HTML element is by make use of the innerHTML property.
To alter 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
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript can Change HTML</h2>
<p id=”p1″>Hello World!</p>
<script>
document.getElementById(“p1”).innerHTML = “New text!”;
</script>
<p>The paragraph above was changed by a script.</p>
</body>
</html>
Output
JavaScript can Change HTML
Hello World!
The paragraph above was changed by a script.
Example explained-
The HTML document above consists a <p> element with id=”p1″
Use the HTML DOM to get the element with id=”p1″
A JavaScript changes the content (innerHTML) of that element to “New text!”
This example changes the content of an <h1> element.
Example
<!DOCTYPE html>
<html>
<body>
<h2 id=”id01″>Old Heading</h2>
<script>
const element = document.getElementById(“id01”);
element.innerHTML = “New Heading”;
</script>
<p>JavaScript changed “Old Heading” to “New Heading”.</p>
</body>
</html>
Output
Old Heading
JavaScript changed "Old Heading" to "New Heading".
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
Let’s go slowly and learn how to use it.
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript HTML DOM</h2>
<img id=”image” src=”smiley.gif” width=”160″ height=”120″>
<script>
document.getElementById(“image”).src = “landscape.jpg”;
</script>
<p>The original image was smiley.gif, but the script changed it to landscape.jpg</p>
</body>
</html>
Output
JavaScript HTML DOM

The original image was smiley.gif, but the script changed it to landscape.jpg
Example explained –
The HTML document above consists of an <img> element with id=”myImage”.
Use the HTML DOM to get the element with id=”myImage”
A JavaScript alters the src attribute of that element from “smiley.gif” to “landscape.jpg”,
Dynamic HTML content
JavaScript is used to create dynamic HTML content.
<!DOCTYPE html>
<html>
<body>
<p id=”demo”></p>
<script>
document.getElementById(“demo”).innerHTML = “Date : ” + Date();
</script>
</body>
</html>
Output
document.write()
In JavaScript, document.write()writes directly to the HTML output stream.
Example
<!DOCTYPE html>
<html>
<body>
<p>Bla, bla, bla</p>
<script>
document.write(Date());
</script>
<p>Bla, bla, bla</p>
</body>
</html>
Output
Bla, bla, bla
Bla, bla, bla