tab preview firefox userchromejs in javascript

To preview userChrome.js modifications in Firefox, you can use the add-on "userChrome.js" by Aris-t2. This add-on allows to preview your changes to userChrome.js in a separate tab, without having to restart Firefox every time.

Here is an example code snippet to add a button to the main Firefox toolbar and preview your userChrome.js in a new browser tab:

index.tsx
// Add a button to the main Firefox toolbar
var button = document.createElement('button');
button.innerHTML = 'Preview userChrome.js';
button.onclick = function() {

  // Open a new tab with the userChrome.js file
  var tab = gBrowser.addTab('chrome://global/content/userChrome.js');

  // Reload the tab to see your modifications
  tab.linkedBrowser.reload();
}
document.getElementById('nav-bar').appendChild(button);
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You can place this snippet in your userChrome.js file to have the button appear in your Firefox toolbar. When you click on the button, a new tab with your userChrome.js file will open, and any modifications you have made will be visible.