event.PreventDefault Vs. event.stopPropagation

The event.preventDefault() prevents the browsers default behaviour, but does not stop the event from bubbling up the DOM. The event.stopPropagation() prevents the event from bubbling up the DOM, but does not stop the browsers default behaviour.

Event capture

Event capture is the process by which an EventListener registered on an ancestor of the event's target can intercept events of a given type before they are received by the event's target. If the capturing EventListener wishes to prevent further processing of the event from occurring it may call the stopPropagation method of the Event interface. This will prevent further dispatch of the event, although additional EventListeners registered at the same hierarchy level will still receive the event. Cancelation is accomplished by calling the Event's preventDefault method. If one or more EventListeners call preventDefault during any phase of event flow the default action will be canceled.

event.preventDefault() example

Browser View

Here we can see, preventDefault only the browsers default action is stopped but the div's click handler still fires. Full Source

<!DOCTYPE html> <html lang="en"> <head> <title>jQuery preventDefault() method</title> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script type="text/javascript"> $(document).ready(function(){ $("#myButton").click(function(event){ event.preventDefault(); }); $("#myDiv").click(function(){ alert("Parent click event fired !"); }); }); </script> </head> <body> <div id="myDiv"> <button id="myButton">button</button> </div> </body> </html>

event.stopPropagation() example

Browser View

Here we can see, with stopPropagation only the buttons click handler is called and the divs click handler never fires. Full Source

<!DOCTYPE html> <html lang="en"> <head> <title>jQuery preventDefault() method</title> <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <script type="text/javascript"> $(document).ready(function(){ $("#myButton").click(function(event){ event.stopPropagation(); }); $("#myDiv").click(function(){ alert("parent click event fired !"); }); }); </script> </head> <body> <div id="myDiv"> <button id="myButton">button</button> </div> </body> </html>

Summary

The event.preventDefault() method on a child will stop the event on the child but it will happen on it's parent (and the ancestors too!).
The event.stopPropagation() method on a child will stop that event from happening on the parent (the entire ancestors).

Next : What are deferred and promise object in jQuery?

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