Javascript DOM HTML Element getElementsByTagName() Method update all matched elements

Introduction

Change the background color of all <p> elements inside a <div> element:

Click the button to add a background color to all p elements inside the div element.

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

<div id="myDIV">
  <p>First p element in div.</p>
  <p>Second p element in div.</p>
  <p>Third p element in div.</p>
</div>

<button onclick="myFunction()">Test</button>

<script>
function myFunction() {
  var x = document.getElementById("myDIV");
  var y = x.getElementsByTagName("P");
  var i;
  for (i = 0; i < y.length; i++) {
    y[i].style.backgroundColor = "red";
  }
}
</script>

</body>
</html>



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