GM_addStyle equivalent in TamperMonkey

Question

Is there a TamperMonkey equivalent to GreaseMonkey's GM_addStyle method for adding CSS?

In GreaseMonkey, you can add a bunch of CSS properties to multiple elements like so:

GM_addStyle("body { color: white; background-color: black; } img { border: 0; }");

To do the equivalent in TamperMonkey, I'm currently having to do the following:

function addGlobalStyle(css) {
    var head, style;
    head = document.getElementsByTagName('head')[0];
    if (!head) { return; }
    style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css;
    head.appendChild(style);
}

addGlobalStyle('body { color: white; background-color: black; }');

This works, but is there a built-in GM_addStyle equivalent for TamperMonkey that saves me from having to repeat this on every script?

Solution 1

According to the TamperMonkey documentation, it supports GM_addStyle directly, like GreaseMonkey does. Check your include/match rules are correct, then add this demo code to the top of your userscript:

GM_addStyle('* { font-size: 99px !important; }');
console.log('ran');

I just tested it on a fresh userscript in Chrome 35 and it worked as expected. If you have any other @grant rule, you will need to add one for this function, otherwise it should be detected and granted automatically.

Solution 2

Version 4.0 or +, update of 2018

ReferenceError: GM_addStyle is not defined

You need to create your own GM_addStyle function, like this :

// ==UserScript==
// @name           Example
// @description    Usercript with GM_addStyle method.
// ==/UserScript==

function GM_addStyle(css) {
  const style = document.getElementById("GM_addStyleBy8626") || (function() {
    const style = document.createElement('style');
    style.type = 'text/css';
    style.id = "GM_addStyleBy8626";
    document.head.appendChild(style);
    return style;
  })();
  const sheet = style.sheet;
  sheet.insertRule(css, (sheet.rules || sheet.cssRules || []).length);
}

//demo :
GM_addStyle("p { color:red; }");
GM_addStyle("p { text-decoration:underline; }");

document.body.innerHTML = "<p>I used GM_addStyle.</p><pre></pre>";

const sheet = document.getElementById("GM_addStyleBy8626").sheet,
  rules = (sheet.rules || sheet.cssRules);

for (let i=0; i<rules.length; i++)
  document.querySelector("pre").innerHTML += rules[i].cssText + "\n";

DEPRECATED

If GM_addStyle(...) doesn't work, check if you have @grant GM_addStyle header.

Like this :

// ==UserScript==
// @name           Example
// @description    See usercript with grant header.
// @grant          GM_addStyle
// ==/UserScript==

GM_addStyle("body { color: white; background-color: black; } img { border: 0; }");

Solution 3

If somebody is interessted, I changed the code so you don't have to write "!important" after every css rule. Of course this only works, if you use the function instead of GM_addStyle.

function addGlobalStyle(css) {
    var head, style;
    head = document.getElementsByTagName('head')[0];
    if (!head) { return; }
    style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css.replace(/;/g, ' !important;');
    head.appendChild(style);
}

The output of this "addGlobalStyle('body { color: white; background-color: black; }');",

will be "body { color: white !important; background-color: black !important; }');"

Solution 4

I was having this same issue. I tried all the fixes, making sure to have // @grant GM_addStyle in the header. My issue was, I also had the default code's // @grant none at the bottom of the header. Removed that piece and now all my css works. Hope this helps someone else if they are stuck on this too.

View more solutions

Comments

[arserbin3]

Heh, I didn't think to test something seemingly unlikely like that .. with its GM_ prefix. They should work on better PageRank of that documentation .. currently invisible on google.com/search?q=tampermonkey+gm_addstyle - Thanks!

[Husky]

This doesn't seem to work, i'm getting ERROR: Execution of script failed! GM_addStyle is not defined messages in the console.

[lpd]

@Husky remember you must grant the function as described in the answer (I wouldn't rely on automatic detection), and obviously any code you inject into the page context will not be able to access the GM functions. I just tested as above and the function still appears to be working fine.

[Black]

There is no info about this in your answer.

[GWu]

Don't forget to add // @grant GM_addStyle in header!

[Malvineous]

As of 2019 GM_addStyle works if you put it in the @grant line too.

[Franklin Yu]

@Malvineous But it’s not documented in official documentation so I tend to think that it’s private API subject to change.

[Franklin Yu]

Oh, functions starting with GM_ is deprecated in Greasemonkey 4, while the new version won’t arrive any time soon.. Yet another reason to write your own!

[dashard]

The GM_addStyle function you posted is perfect. If it's not working make sure to add a listener in case the DOM target is not fully loaded. ;)

[mrpandey]

I suggest using backticks instead of quotes if you want to write CSS in multiple lines inside GM_addStyle.

[Nils Lindemann]

Please add @GWu s example to your answer.