Cancel onbeforeunload event handler?

Question

I have an onbeforeunload event handler attached to the page which executes every time the page reloads / gets redirected.

window.onbeforeunload = function() { console.log("do something");}

I do not want this script to run during my tests. I want to disable it in my own test environment.

Is there some way to unbind this onbeforeunload event? I am using JavaScript, with jQuery as the framework, so an answer in jQuery would be good.

Zerium · Accepted Answer · 2012-11-20 10:10:09Z

56

In javascript functions can be overwritten. You can simply assign it a new purpose:

window.onbeforeunload = function () { // blank function do nothing }

This will completely overwrite the existing version of window.onbeforeunload.

Note: Why don't you simply remove the line of code that sets this function in the first place? Or if you can't, you will have to set this blank function after it is has been defined, just to make sure it is not overridden again

edited Nov 20, 2012 at 10:10

Zerium

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answered Jun 9, 2011 at 5:22

Ibu

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4 Comments

akahunahi Over a year ago

This worked perfectly inside our AJAX functions that hit this same problem. +1

Limon Monte Over a year ago

or window.onbeforeunload = null;

Pasupathi Rajamanickam Over a year ago

This is not overriding once previous method called. If previous method called once, even after assigning new one not helping in my case. It still goes to previous method.

Ibu Over a year ago

You can only override it before it is called.

Oleksandr Potomkin · Accepted Answer · 2019-12-11 14:18:06Z

To add:

function f_beforeunload(e) {console.log("do something");} window.addEventListener("beforeunload", f_beforeunload);

To remove:

window.removeEventListener("beforeunload", f_beforeunload);

E_net4 · Accepted Answer · 2019-02-13 14:09:40Z

4

Not immediately related to this question, but may help someone nevertheless. This is what I use in Angular 1.x and TypeScript:

this.$window.onbeforeunload = () => undefined;

edited Feb 13, 2019 at 14:09

E_net4

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answered Dec 20, 2016 at 15:20

Simon

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4 Comments

Ibu Over a year ago

Maybe because this requires angular and TypeScript to do something that can be done in a single line of code without it.

Simon Over a year ago

Perhaps, but I explicitly stated that while slightly unrelated, someone who may be using Angular may find use in this. TypeScript in this code is irrelevant - it just happened to be what's part of my setup. I can understand not up-voting but down-voting is a bit petty. Then again, maybe I'm getting my jimmies in a twist here.

nathan felix Over a year ago

FYI: this method causes IE11 to show the confirmation message with the message "null". Replacing null with undefined fixes it.

rybo111 Over a year ago

Does it have to be a function? The default value of onbeforeload is null, so can't you just set it to null? this.$window.onbeforeunload = null;

murthy naika k · Accepted Answer · 2020-01-16 10:16:38Z

jQuery ≥ 1.7

With jQuery 1.7 onward the event API has been updated, .bind()/.unbind() are still available for backwards compatibility, but the preferred method is using the on()/off() functions. The below would now be,

$('#myimage').click(function() { return false; }); // Adds another click event $('#myimage').off('click'); $('#myimage').on('click.mynamespace', function() { /* Do stuff */ }); $('#myimage').off('click.mynamespace'); $( window ).on( "unload", handler )

As the .unload() method is just a shorthand for .on( "unload", handler ), detaching is possible using .off( "unload" )

$( window ).off( "unload", handler )

As the .unload() method is just a shorthand for .on( "unload", handler ), detaching is possible using .off( "unload" )
@murthynaikak unload != onbeforeunload hence the onbefore

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