GM API Reference

CodeTweak provides a suite of GreaseMonkey (GM) compatible APIs to help you build powerful userscripts. These APIs allow you to perform tasks that standard browser scripts cannot, such as cross-origin networking, persistent data storage, and browser-level notifications.

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API Categories

Browse the available APIs by category:

• Storage & Data: Save and load data across sessions, and listen for changes.
• UI & Elements: Modify the browser's interface and the page's DOM.
• Network & Clipboard: Make cross-origin requests and interact with the system clipboard.
• Resources: Access external assets defined in your metadata.
• Advanced & Utility: Advanced features like unsafeWindow and error reporting.

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The GM and GM_ Namespaces

CodeTweak supports both the traditional synchronous Greasemonkey 3 style and the asynchronous Greasemonkey 4 style:

Synchronous (GM3 Style)

Most functions are prefixed with GM_ and return values immediately.

const value = GM_getValue('key', 'default');
GM_setValue('key', 'new value');

Asynchronous (GM4 Style)

All functions are available under the GM object and return a Promise.

const value = await GM.getValue('key', 'default');
await GM.setValue('key', 'new value');

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Requesting Permissions

To use any of these APIs, you must explicitly declare them in your script's metadata block using the @grant tag:

// ==UserScript==
// @name        My Script
// @match       https://example.com/*
// @grant       GM_setValue
// @grant       GM_getValue
// @grant       GM_xmlhttpRequest
// ==/UserScript==

If your script doesn't need any special APIs, use @grant none.