Javascript DOM HTML Element querySelectorAll() Method get all elements by class name in <div>

Introduction

Set the background color of all elements with class="example" in a <div> element:

Click the button to add a background color to all elements with class="example" inside DIV.

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<!DOCTYPE html>
<html>
<head>
<style>
#myDIV {/*from  w w  w.  j a  v a 2  s .  c o  m*/
  border: 1px solid black;
  margin: 5px;
}
</style>
</head>
<body>

<div id="myDIV">
  <h2 class="example">A heading with class="example" in div</h2>
  <p class="example">A p element with class="example" in a div.</p>
  <p class="example">Another p element with class="example" in a div.</p>
  <p>A p element in div with a <span class="example">span element with class="example"</span> inside of it.</p>
</div>
<button onclick="myFunction()">Test</button>
<script>
function myFunction() {
  var x = document.getElementById("myDIV").querySelectorAll(".example");
  var i;
  for (i = 0; i < x.length; i++) {
    x[i].style.backgroundColor = "red";
  }
}
</script>

</body>
</html>



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