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How to create config preference via user.js file without manually editing through about:config portal?

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  • Last reply by CJ36

CJ36
CJ36
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I'm interested in creating a new configuration preference for my user-agent (general.useragent.override). I know how to manually create one via about:config; however, it is overwritten by my user.js file every launch.

Is there a way to create an entry in the user.js file for a preference that does not exist?

General syntax: user_pref("general.useragent.override",Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0);

But obviously, this causes an error since that preference does not exist.

Thanks for the help!

I'm interested in creating a new configuration preference for my user-agent (general.useragent.override). I know how to manually create one via about:config; however, it is overwritten by my user.js file every launch. Is there a way to create an entry in the user.js file for a preference that does not exist? General syntax: user_pref("general.useragent.override",Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0); But obviously, this causes an error since that preference does not exist. Thanks for the help!

Chosen solution

NVM...

To answer my questions...YES you can create a new config preference via the user.js file. Just don't be special like myself and use incorrect syntax.

The correct syntax: user_pref("general.useragent.override","Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0");

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CJ36
CJ36 Question owner
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Chosen Solution

NVM...

To answer my questions...YES you can create a new config preference via the user.js file. Just don't be special like myself and use incorrect syntax.

The correct syntax: user_pref("general.useragent.override","Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0");