InnerHTML In JavaScript

The DOM innerHTML property can be used to modify your document's HTML on the fly.

When you use innerHTML, you can change the page's content without refreshing the page. This can make your website feel quicker and more responsive to user input.

The innerHTML property is used along with getElementById within your JavaScript code to refer to an HTML element and change its contents.

Strictly speaking, the innerHTML property is not part of the official DOM specification. Despite this, it is supported in all major browsers, and has had widespread use across the web for many years. DOM, which stands for Document Object Model, is the hierarchy that you can use to access and manipulate HTML objects from within your JavaScript.

The innerHTML Syntax

The syntax for using innerHTML goes like this:

In this syntax example, {ID of element} is the ID of an HTML element and {content} is the new content to go into the element.

Basic innerHTML Example

Here's a basic example to demonstrate how innerHTML works.

This code includes two functions and two buttons. Each function displays a different message and each button triggers a different function.

In the functions, the getElementById refers to the HTML element by using its ID. We give the HTML element an ID of "myText" using id="myText".

So in the first function for example, you can see that document.getElementById('myText').innerHTML = 'Thanks!'; is setting the innerHTML of the "myText" element to "Thanks!".

Code:

<script type="text/javascript">
function Msg1(){
  document.getElementById('myText').innerHTML = 'Thanks!';
}
function Msg2(){
  document.getElementById('myText').innerHTML = 'Try message 1 again...';
}
</script>
<input type="button" onclick="Msg1()" value="Show Message 1" />
<input type="button"  onclick="Msg2()" value="Show Message 2" />
<p id="myText"></p> 

Result:

Example 2: innerHTML With User Input

Here's an example of using innerHTML with a text field. Here, we display whatever the user has entered into the input field.

Code:

<script type="text/javascript">
function showMsg(){
  var userInput = document.getElementById('userInput').value;
  document.getElementById('userMsg').innerHTML = userInput;
}
</script>
<input type="input" maxlength="40" id="userInput" 
  onkeyup="showMsg()" value="Enter text here..." />
<p id="userMsg"></p> 

Result:

Example 3: Formatting with innerHTML

In this example, we use the innerHTML property to detect the color that the user has selected. We can then use style.color to apply the new color. In both cases, we refer to the HTML elements by their ID (using getElementById.)

Code:

<script type="text/javascript">
function changeColor(){
  var newColor = document.getElementById('colorPicker').value;
	document.getElementById('colorMsg').style.color = newColor;
}
</script>
<p id="colorMsg">Choose a color...</p> 
<select id="colorPicker" onchange="JavaScript:changeColor()">
<option value="#000000">Black</option>
<option value="#000099">Blue</option>
<option value="#990000">Red</option>
<option value="#009900">Green</option>
</select>

Result:

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