How to make a script redirect only once every time an appropriate page loads?

Question

I'm writing a Tampermonkey script that I want to use to redirect from youtube.com/* to a YouTube channel address.

window.addEventListener ("load", LocalMain, false);

function LocalMain () {
    location.replace("https://www.youtube.com/channel/*");
}

When the script is running it redirects to the channel URL but then keeps running and continuously redirects.

Try setting up a cookie for youtube named "hasRedirect" and if it is not defined, redirect. Otherwise, if it is already defined, don't redirect. — k3llydev, Apr 12 '19 at 15:20
Near duplicate of https://stackoverflow.com/questions/10675049/greasemonkey-add-parameters-to-url and many others. — Brock Adams, Apr 13 '19 at 17:03

charlietfl · Answer 1 · 2019-04-12T15:41:22.357

2

You need to check if the current pathname includes channel before reassigning a new href

function LocalMain () {

     if(!location.pathname.includes('/channel/')) {
        location.replace("https://www.youtube.com/channel/*");
     }
}

Also note you don't need to window load event to complete to do this

edited Apr 12 '19 at 15:41

answered Apr 12 '19 at 15:24

charlietfl

170,828
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Harry Chilinguerian · Answer 2 · 2019-04-12T15:39:19.277

2

You could check to see if the location contains 'channel', then return before you change the location.

window.addEventListener ("load", LocalMain, false);

function LocalMain () {
    if(location.href.indexOf('channel') === -1) return;
    location.replace("https://www.youtube.com/channel/*");
}

edited Apr 12 '19 at 15:39

answered Apr 12 '19 at 15:24

Harry Chilinguerian

563
3
9

1

Don't think location object has a contains method – charlietfl Apr 12 '19 at 15:26
@charlietfl, thank you for the catch sometimes I load some convienience methods into my browser. In this case it tripped me up. – Harry Chilinguerian Apr 12 '19 at 15:33
1

OK...but edit still won't work... `location` is an object not string – charlietfl Apr 12 '19 at 15:34
@charlietfl, Ok checked it this time it works with the href property which is what I was thinking but not coding. Thank you once again for the correction. – Harry Chilinguerian Apr 12 '19 at 15:40

score 2 · Accepted Answer · answered Apr 12 '19 at 17:35

The standard, much more efficient, and much faster performing way to do this kind of redirect is to tune the script's metadata to not even run on the redirected-to page.

Also, use // @run-at document-start for even better response.

So your script would become something like:

// ==UserScript==
// @name        YouTube, Redirect to my channel
// @match       https://www.youtube.com/*
// @exclude     https://www.youtube.com/channel/*
// @run-at      document-start
// ==/UserScript==

location.replace("https://www.youtube.com/channel/UC8VkNBOwvsTlFjoSnNSMmxw");

Also, for such "broad spectrum" redirect scripts, consider using location.assign() so that you or your user can recover the original URL in the history in case of an overzealous redirect.

score 0 · Answer 4 · answered Apr 12 '19 at 15:26

Is tampermonkey configured to run the script only when not on your channel URL?

If not... then your script might ironically be doing exactly what you want: running once each page load. And the script loads a new page.

You can fix this within the script, like this:

window.addEventListener ('load', localMain, false);

function localMain () {
    if (location.href.startsWith('https://www.youtube.com/channel/')) {
        return; // exit
    }
    location.replace('https://www.youtube.com/channel/*');
}

How to make a script redirect only once every time an appropriate page loads?

4 Answers4

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