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UserUtils

Library with various utilities for userscripts - register listeners for when CSS selectors exist, intercept events, manage persistent user configurations, modify the DOM more easily and more.
Contains builtin TypeScript declarations. Webpack compatible and supports ESM and CJS.
Licensed under the MIT license.

You may want to check out my template for userscripts in TypeScript that you can use to get started quickly. It also includes this library by default.

If you like using this library, please consider supporting the development ❤️

Full documentation on GitHub

Features:

• DOM:
  • onSelector() - call a listener once a selector is found in the DOM
  • initOnSelector() - needs to be called once to be able to use onSelector()
  • getSelectorMap() - returns all currently registered selectors, listeners and options
  • getUnsafeWindow() - get the unsafeWindow object or fall back to the regular window object
  • insertAfter() - insert an element as a sibling after another element
  • addParent() - add a parent element around another element
  • addGlobalStyle() - add a global style to the page
  • preloadImages() - preload images into the browser cache for faster loading later on
  • openInNewTab() - open a link in a new tab
  • interceptEvent() - conditionally intercepts events registered by addEventListener() on any given EventTarget object
  • interceptWindowEvent() - conditionally intercepts events registered by addEventListener() on the window object
  • amplifyMedia() - amplify an audio or video element's volume past the maximum of 100%
  • isScrollable() - check if an element has a horizontal or vertical scroll bar
• Math:
  • clamp() - constrain a number between a min and max value
  • mapRange() - map a number from one range to the same spot in another range
  • randRange() - generate a random number between a min and max boundary
• Misc:
  • ConfigManager() - class that manages persistent userscript configurations, including data migration
  • autoPlural() - automatically pluralize a string
  • pauseFor() - pause the execution of a function for a given amount of time
  • debounce() - call a function only once, after a given amount of time
  • fetchAdvanced() - wrapper around the fetch API with a timeout option
• Arrays:
  • randomItem() - returns a random item from an array
  • randomItemIndex() - returns a tuple of a random item and its index from an array
  • takeRandomItem() - returns a random item from an array and mutates it to remove the item
  • randomizeArray() - returns a copy of the array with its items in a random order

Installation:

• If you are using a bundler like webpack, you can install this package using npm:

  npm i @sv443-network/userutils
  

  Then, import it in your script as usual:

  import { addGlobalStyle } from "@sv443-network/userutils";
  
  // or just import everything (not recommended because this doesn't allow for treeshaking):
  
  import * as UserUtils from "@sv443-network/userutils";
  

  Shameless plug: I made a webpack-based template for userscripts in TypeScript that you can use to get started quickly. It also includes this library by default.

• If you are not using a bundler, you can include the latest release from GreasyFork by adding this directive to the userscript header:

  // @require https://greasyfork.org.cn/scripts/472956-userutils/code/UserUtils.js
  

  Then, access the functions on the global variable UserUtils:

  UserUtils.addGlobalStyle("body { background-color: red; }");
  
  // or using object destructuring:
  
  const { clamp } = UserUtils;
  console.log(clamp(1, 5, 10); // 5