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JavaScript HTML DOM - Changing HTML

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The HTML DOM allows JavaScript to change the content of HTML elements.

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 »

Example explained:

  • The HTML document above contains a <p> element with id="p1"
  • We 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>

<h1 id="id01">Old Heading</h1>

<script>
const element = document.getElementById("id01");
element.innerHTML = "New Heading";
</script>

</body>
</html>
Try it Yourself »

Example explained:

  • The HTML document above contains an <h1> element with id="id01"
  • We use the HTML DOM to get the element with id="id01"
  • A JavaScript changes the content (innerHTML) of that element 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

<!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"

Dynamic HTML content

JavaScript can create dynamic HTML content:

Example

<!DOCTYPE html>
<html>
<body>

<script>
document.getElementById("demo").innerHTML = "Date : " + Date(); </script>

</body>
</html>
Try it Yourself »

document.write()

In JavaScript, document.write() can be used to write 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>
Try it Yourself »

Never use document.write() after the document is loaded. It will overwrite the document.

Test Yourself With Exercises

Exercise:

Use HTML DOM to change the value of the image's src attribute.

<img id="image" src="smiley.gif">

<script>
document.getElementById("image") = "pic_mountain.jpg";
</script>

Start the Exercise

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