Javascript Reference - HTML DOM querySelector() Method

The querySelector() method returns the first element that matches a specified CSS selector(s) in the document.

Browser Support


`querySelector`	Yes	8.0	Yes	Yes	Yes

Syntax

document.querySelector(CSS selectors)

Parameter Values

Parameter	Type	Description
CSS selectors	String	Required. CSS selectors to match the element.

Technical Details

DOM Version:	Selectors Level 1 Document Object
Return Value:	A NodeList object, representing the first element that matches the specified CSS selector(s).

Example

The following code shows how to get the first element in the document with class="example":


<!DOCTYPE html>
<html>
<body>
<h2 class="example">A heading </h2>
<p class="example">A paragraph.</p> 
<button onclick="myFunction()">test</button>
<!-- w  w w  .  ja  va  2  s. co m-->
<script>
function myFunction() {
    document.querySelector(".example").style.backgroundColor = "red";
}
</script>

</body>
</html>

The code above is rendered as follows:

Example 2

The following code shows how to get the first <p> element in the document.


<!DOCTYPE html>
<html>
<body>
<p>This is a p element.</p>
<p>This is also a p element.</p>
<button onclick="myFunction()">test</button>
<script>
function myFunction() {<!--from  www  .  j av  a 2s  .  c o  m-->
    document.querySelector("p").style.backgroundColor = "red";
}
</script>

</body>
</html>

The code above is rendered as follows:

Example 3

The following code shows how to get the first <p> element in the document with class="example".


<!DOCTYPE html>
<html>
<body>
<h2 class="example">A heading</h2>
<p class="example">A paragraph</p> 
<button onclick="myFunction()">test</button>
<script>
function myFunction() {<!--from w  w w .  ja  v a2s  . c om-->
    document.querySelector("p.example").style.backgroundColor = "red";
}
</script>

</body>
</html>

The code above is rendered as follows:

Example 4

The following code shows how to change the text of an element with id="demo".


<!DOCTYPE html>
<html>
<body>
<p id="demo">This is a p element.</p>
<button onclick="myFunction()">test</button>
<script>
function myFunction() {<!--from   w ww  . j  a v  a2s.  c  o  m-->
    document.querySelector("#demo").innerHTML = "Hello World!";
}
</script>

</body>
</html>

The code above is rendered as follows: