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What is the use of stopPropagation method in JavaScript

WBOYforward: 2023-08-24 17:05:06695browse

This article will introduce the stopPropagation() method along with useful code examples. After that, we will understand the difference between stopPropagation() and PreventDefault() methods.

stopPropagation() event method - Parent elements cannot access events using this method method. Generally speaking, this function is created to prevent multiple calls to the same event spread. For example, if a button element is contained within a div tag, and they both have a onclick event, whenever we try to activate the event associated with the button element, The event associated with the div element will also be fired because the div element is indeed Button element.

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event.stopPropagation();

stopPropagation() method will block the parent access event and can be used solve this problem.

Example 1

<!DOCTYPE html>
<html>
<title>What is the use of stopPropagation method in JavaScript - TutorialsPoint</title>
<head>
   <meta charset="UTF-8">
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <style>
      div {
         padding: 50px;
         background-color: rgba(10, 111, 134, 0.2);
         text-align: center;
         cursor: pointer;
      }
   </style>
   <!-- jQuery library -->
   <script src="https://code.jquery.com/jquery-git.js"></script>
</head>
<body>
   <h1>Let us understand the stopPropagation() Method</h1>
   <p>Test the results by clicking the DIV(1) & DIV(2) as shown below in the color boxes:</p>
   <div onclick="myFunction2()">This is my Second DIV(2)
      <div onclick="myFunction1(event)">This is my First DIV(1)</div>
   </div>
   Check to stop propagation event:
   <input type="checkbox" id="check">
   <p></p>
   <p>Because my First DIV(1) is inside Second DIV(2), both DIVs get clicked when you click on First DIV(1).
   </p>
   <p>You can test it by check and uncheck the stop propagation checkbox, to get the outcome.</p>
   <p>You can stop the current event from propagating by using the stopPropagation() method.</p>
   <script>
      function myFunction1(event) {
         alert("My First DIV(1)");
         if (document.getElementById("check").checked) {
            event.stopPropagation();
         }
      }
      function myFunction2() {
         alert("My Second DIV(2)");
      }
   </script>
</body>
</html>

After clicking on the outer div "my Second DIV(2)", the confirmation box is only displayed once, as shown below.

Additionally, if you click on the inner div "my First DIV(1)", the confirmation box will be displayed twice as shown below.

Next, after clicking the "OK" button, the outer div "My Second DIV(2)" confirmation box will be displayed.

Just check a checkbox and click the inner div "my First DIV(1)" like Screenshot below. The confirmation box only appears once.

Example 2

In this example, let us understand how the event.stopPropagation() method is implemented, This will cause a single function to be executed on the button element.

<!DOCTYPE html>
<html>
<title>What is the use of stopPropagation method in JavaScript - TutorialsPoint</title>
<head>
   <meta charset="UTF-8">
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
   <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
   <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
   <style>
      div {
         padding: 50px;
         background-color: rgba(63, 65, 45, 0.2);
         text-align: center;
      }
   </style>
   
   <!-- jQuery library -->
   <script src="https://code.jquery.com/jquery-git.js"></script>
</head>
<body>
   <h3>The button element's single function will be executed with stopPropagation() Method
   </h3>
   <p>Test the result by clicking the button as shown below in the color boxe:</p>
   <div class="first" onclick="functionFirst()">
      <button type="button" class="btn btn-success btn-lg" onclick="functionSecond()">
         Button
      </button>
   </div>
   <p></p>
   <script>
      function functionSecond() {
         event.stopPropagation();
         alert("This is my First DIV(1)");
      }

      function functionFirst() {
         alert("This is my Second DIV(2)");
      }
   </script>
</body>
</html>

preventDefault() method - This is the method found in the event interface. By using this method, Prevents the browser from performing the default action for the selected element. only if If the technology is able to do this, the event is cancelable. For example, the scroll and wheel events are Some examples of unavoidable events.

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preventDefault() Method

Example 3

Let’s understand how to prevent a link from following the URL in this example so that it is inaccessible to the browser Visit another page.

<!DOCTYPE html>
<html>
<title>What is the use of stopPropagation method in JavaScript - TutorialsPoint</title>
<head>
   <meta charset="UTF-8">
   <meta http-equiv="X-UA-Compatible" content="IE=edge">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <!-- Using jquery library -->
   <script src="https://code.jquery.com/jquery-git.js"></script>
</head>
<body>
   <a id="myLink" href="www.tutorialspoint.com">
      Welcome to Tutorialspoint!
   </a>
   <script>
      $("#myLink").click(function() {
         event.preventDefault();
         alert("This event is prevented, you can't visit the URL.");
      });
   </script>
</body>
</html>

Click the link and you will see a confirmation box that says "This event has been blocked and you cannot access the URL."

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What is the use of stopPropagation method in JavaScript

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Example 1

Example 2

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Example 3

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