UserUtils

Zero-dependency 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. Fully web compatible and supports ESM and CJS imports and global declaration.
If you like using this library, please consider supporting the development ❤️

_{View the documentation of previous major releases: 4.2.1, 3.0.0, 2.0.1, 1.2.0, 0.5.3}

Installation
Preamble (info about the documentation)
License
Features
- DOM:
  - SelectorObserver - class that manages listeners that are called when selectors are found in the DOM
  - 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
  - isScrollable() - check if an element has a horizontal or vertical scroll bar
  - observeElementProp() - observe changes to an element's property that can't be observed with MutationObserver
- 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
  - randomId() - generate a random ID of a given length and radix
- 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
  - insertValues() - insert values into a string at specified placeholders
  - compress() - compress a string with Gzip or Deflate
  - decompress() - decompress a previously compressed string
- 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
- Translation:
  - tr() - simple translation of a string to another language
  - tr.addLanguage() - add a language and its translations
  - tr.setLanguage() - set the currently active language for translations
  - tr.getLanguage() - returns the currently active language
- Utility types for TypeScript:
  - Stringifiable - any value that is a string or can be converted to one (implicitly or explicitly)
  - NonEmptyArray - any array that should have at least one item
  - NonEmptyString - any string that should have at least one character
  - LooseUnion - a union that gives autocomplete in the IDE but also allows any other value of the same type

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 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 by adding one of these directives to the userscript header, depending on your preferred CDN:
```
// @require https://greasyfork.org/scripts/472956-userutils/code/UserUtils.js
```
```
// @require https://openuserjs.org/src/libs/Sv443/UserUtils.js
```
(in order for your userscript not to break on a major library update, use the versioned URL at the top of the GreasyFork page)

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
```

Preamble:

This library is written in TypeScript and contains builtin TypeScript declarations.

Each feature has example code that can be expanded by clicking on the text "Example - click to view".
The usages and examples are written in TypeScript and use ESM import syntax, but the library can also be used in plain JavaScript after removing the type annotations (and changing the imports if you are using CommonJS or the global declaration).
If the usage section contains multiple usages of the function, each occurrence represents an overload and you can choose which one you want to use.

Some features require the @run-at or @grant directives to be tweaked in the userscript header or have other requirements.
Their documentation will contain a section marked by a warning emoji (⚠️) that will go into more detail.

License:

This library is licensed under the MIT License.
See the license file for details.

Features:

DOM:

SelectorObserver

Usage:

new SelectorObserver(baseElement: Element, options?: SelectorObserverOptions)
new SelectorObserver(baseElementSelector: string, options?: SelectorObserverOptions)

A class that manages listeners that are called when elements at given selectors are found in the DOM.
This is useful for userscripts that need to wait for elements to be added to the DOM at an indeterminate point in time before they can be interacted with.

The constructor takes a baseElement, which is a parent of the elements you want to observe.
If a selector string is passed instead, it will be used to find the element.
If you want to observe the entire document, you can pass document.body

The options parameter is optional and will be passed to the MutationObserver that is used internally.
The MutationObserver options present by default are { childList: true, subtree: true } - you may see the MutationObserver.observe() documentation for more information and a list of options.
For example, if you want to trigger the listeners when certain attributes change, pass { attributeFilter: ["class", "data-my-attribute"] }

Additionally, there are the following extra options:

disableOnNoListeners - whether to disable the SelectorObserver when there are no listeners left (defaults to false)
enableOnAddListener - whether to enable the SelectorObserver when a new listener is added (defaults to true)
defaultDebounce - if set to a number, this debounce will be applied to every listener that doesn't have a custom debounce set (defaults to 0)

⚠️ Make sure to call enable() to actually start observing. This will need to be done after the DOM has loaded (when using @run-at document-end or after DOMContentLoaded has fired) and as soon as the baseElement or baseElementSelector is available.

Methods:

addListener<TElement = HTMLElement>(selector: string, options: SelectorListenerOptions): void
Adds a listener (specified in options.listener) for the given selector that will be called once the selector exists in the DOM. It will be passed the element(s) that match the selector as the only argument.
The listener will be called immediately if the selector already exists in the DOM.

options.listener is the only required property of the options object.
It is a function that will be called once the selector exists in the DOM.
It will be passed the found element or NodeList of elements, depending on if options.all is set to true or false.

If options.all is set to true, querySelectorAll() will be used instead and the listener will be passed a NodeList of matching elements.
This will also include elements that were already found in a previous listener call.
If set to false (default), querySelector() will be used and only the first matching element will be returned.

If options.continuous is set to true, the listener will not be deregistered after it was called once (defaults to false).

⚠️ You should keep usage of this option to a minimum, as it will cause the listener to be called every time the selector is checked for and found and this can stack up quite quickly.
⚠️ You should try to only use this option on SelectorObserver instances that are scoped really low in the DOM tree to prevent as many selector checks as possible from being triggered.
⚠️ I also recommend always setting a debounce time (see constructor or below) if you use this option.

If options.debounce is set to a number above 0, the listener will be debounced by that amount of milliseconds (defaults to 0).
E.g. if the debounce time is set to 200 and the selector is found twice within 100ms, only the last call of the listener will be executed.

When using TypeScript, the generic TElement can be used to specify the type of the element(s) that the listener will return.
It will default to HTMLElement if left undefined.

enable(immediatelyCheckSelectors?: boolean): boolean
Enables the observation of the child elements for the first time or if it was disabled before.
immediatelyCheckSelectors is set to true by default, which means all previously registered selectors will be checked. Set to false to only check them on the first detected mutation.
Returns true if the observation was enabled, false if it was already enabled or the passed baseElementSelector couldn't be found.

disable(): void
Disables the observation of the child elements.
If selectors are currently being checked, the current selector will be finished before disabling.

isEnabled(): boolean
Returns whether the observation of the child elements is currently enabled.

clearListeners(): void
Removes all listeners for all selectors.

removeAllListeners(selector: string): boolean
Removes all listeners for the given selector.

removeListener(selector: string, options: SelectorListenerOptions): boolean
Removes a specific listener for the given selector and options.

getAllListeners(): Map<string, SelectorListenerOptions[]>
Returns a Map of all selectors and their listeners.

getListeners(selector: string): SelectorListenerOptions[] | undefined
Returns all listeners for the given selector or undefined if there are none.

Examples - click to view

Basic usage:

import { SelectorObserver } from "@sv443-network/userutils";

// adding a single-shot listener before the element exists:
const fooObserver = new SelectorObserver("body");

fooObserver.addListener("#my-element", {
  listener: (element) => {
    console.log("Element found:", element);
  },
});

document.addEventListener("DOMContentLoaded", () => {
  // starting observation after the <body> element is available:
  fooObserver.enable();


  // adding custom observer options:

  const barObserver = new SelectorObserver(document.body, {
    // only check if the following attributes change:
    attributeFilter: ["class", "style", "data-whatever"],
    // debounce all listeners by 100ms unless specified otherwise:
    defaultDebounce: 100,
  });

  barObserver.addListener("#my-element", {
    listener: (element) => {
      console.log("Element's attributes changed:", element);
    },
  });

  barObserver.addListener("#my-other-element", {
    // set the debounce higher than provided by the defaultDebounce property:
    debounce: 250,
    listener: (element) => {
      console.log("Other element's attributes changed:", element);
    },
  });

  barObserver.enable();


  // using custom listener options:

  const bazObserver = new SelectorObserver(document.body);

  // for TypeScript, specify that input elements are returned by the listener:
  bazObserver.addListener<HTMLInputElement>("input", {
    all: true,        // use querySelectorAll() instead of querySelector()
    continuous: true, // don't remove the listener after it was called once
    debounce: 50,     // debounce the listener by 50ms
    listener: (elements) => {
      // type of `elements` is NodeListOf<HTMLInputElement>
      console.log("Input elements found:", elements);
    },
  });

  bazObserver.enable();


  // use a different element as the base:

  const myElement = document.querySelector("#my-element");
  if(myElement) {
    const quxObserver = new SelectorObserver(myElement);

    quxObserver.addListener("#my-child-element", {
      listener: (element) => {
        console.log("Child element found:", element);
      },
    });

    quxObserver.enable();
  }
});

Get and remove listeners:

import { SelectorObserver } from "@sv443-network/userutils";

document.addEventListener("DOMContentLoaded", () => {
  const observer = new SelectorObserver(document.body);

  observer.addListener("#my-element-foo", {
    continuous: true,
    listener: (element) => {
      console.log("Element found:", element);
    },
  });

  observer.addListener("#my-element-bar", {
    listener: (element) => {
      console.log("Element found again:", element);
    },
  });

  observer.enable();


  // get all listeners:

  console.log(observer.getAllListeners());
  // Map(2) {
  //   '#my-element-foo' => [ { listener: [Function: listener] } ],
  //   '#my-element-bar' => [ { listener: [Function: listener] } ]
  // }


  // get listeners for a specific selector:

  console.log(observer.getListeners("#my-element-foo"));
  // [ { listener: [Function: listener], continuous: true } ]


  // remove all listeners for a specific selector:

  observer.removeAllListeners("#my-element-foo");
  console.log(observer.getAllListeners());
  // Map(1) {
  //   '#my-element-bar' => [ { listener: [Function: listener] } ]
  // }
});

Chaining:

import { SelectorObserver } from "@sv443-network/userutils";
import type { SelectorObserverOptions } from "@sv443-network/userutils";

// apply a default debounce to all SelectorObserver instances:
const defaultOptions: SelectorObserverOptions = {
  defaultDebounce: 100,
};

document.addEventListener("DOMContentLoaded", () => {
  // initialize generic observer that in turn initializes "sub-observers":
  const fooObserver = new SelectorObserver(document.body, {
    ...defaultOptions,
    // define any other specific options here
  });

  const myElementSelector = "#my-element";

  // this relatively expensive listener (as it is in the full <body> scope) will only fire once:
  fooObserver.addListener(myElementSelector, {
    listener: (element) => {
      // only enable barObserver once its baseElement exists:
      barObserver.enable();
    },
  });

  // barObserver is created at the same time as fooObserver, but only enabled once #my-element exists
  const barObserver = new SelectorObserver(element, {
    ...defaultOptions,
    // define any other specific options here
  });

  // this selector will be checked for immediately after `enable()` is called
  // and on each subsequent mutation because `continuous` is set to true.
  // however it is much less expensive as it is scoped to a lower element which will receive less DOM updates
  barObserver.addListener(".my-child-element", {
    all: true,
    continuous: true,
    listener: (elements) => {
      console.log("Child elements found:", elements);
    },
  });

  // immediately enable fooObserver as the <body> is available as soon as "DOMContentLoaded" fires:
  fooObserver.enable();
});

getUnsafeWindow()

Usage:

getUnsafeWindow(): Window

Returns the unsafeWindow object or falls back to the regular window object if the @grant unsafeWindow is not given.
Userscripts are sandboxed and do not have access to the regular window object, so this function is useful for websites that reject some events that were dispatched by the userscript.

Example - click to view

import { getUnsafeWindow } from "@sv443-network/userutils";

// trick the site into thinking the mouse was moved:
const mouseEvent = new MouseEvent("mousemove", {
  view: getUnsafeWindow(),
  screenY: 69,
  screenX: 420,
  movementX: 10,
  movementY: 0,
});

document.body.dispatchEvent(mouseEvent);

insertAfter()

Usage:

insertAfter(beforeElement: Element, afterElement: Element): Element

Inserts the element passed as afterElement as a sibling after the passed beforeElement.
The passed afterElement will be returned.

⚠️ This function needs to be run after the DOM has loaded (when using @run-at document-end or after DOMContentLoaded has fired).

Example - click to view

import { insertAfter } from "@sv443-network/userutils";

// insert a <div> as a sibling next to an element
const beforeElement = document.querySelector("#before");
const afterElement = document.createElement("div");
afterElement.innerText = "After";

insertAfter(beforeElement, afterElement);

addParent()

Usage:

addParent(element: Element, newParent: Element): Element

Adds a parent element around the passed element and returns the new parent.
Previously registered event listeners are kept intact.

⚠️ This function needs to be run after the DOM has loaded (when using @run-at document-end or after DOMContentLoaded has fired).

Example - click to view

import { addParent } from "@sv443-network/userutils";

// add an <a> around an element
const element = document.querySelector("#element");
const newParent = document.createElement("a");
newParent.href = "https://example.org/";

addParent(element, newParent);

addGlobalStyle()

Usage:

addGlobalStyle(css: string): HTMLStyleElement

Adds a global style to the page in form of a <style> element that's inserted into the <head>.
Returns the style element that was just created.
⚠️ This function needs to be run after the DOM has loaded (when using @run-at document-end or after DOMContentLoaded has fired).

Example - click to view

import { addGlobalStyle } from "@sv443-network/userutils";

document.addEventListener("DOMContentLoaded", () => {
  addGlobalStyle(`
    body {
      background-color: red;
    }
  `);
});

preloadImages()

Usage:

preloadImages(urls: string[], rejects?: boolean): Promise<void>

Preloads images into browser cache by creating an invisible <img> element for each URL passed.
The images will be loaded in parallel and the returned Promise will only resolve once all images have been loaded.
The resulting PromiseSettledResult array will contain the image elements if resolved, or an ErrorEvent if rejected, but only if rejects is set to true.

Example - click to view

import { preloadImages } from "@sv443-network/userutils";

preloadImages([
  "https://example.org/image1.png",
  "https://example.org/image2.png",
  "https://example.org/image3.png",
], true)
  .then((results) => {
    console.log("Images preloaded. Results:", results);
  })
  .catch((results) => {
    console.error("Couldn't preload all images. Results:", results);
  });

openInNewTab()

Usage:

openInNewTab(url: string): void

Creates an invisible anchor with a _blank target and clicks it.
Contrary to window.open(), this has a lesser chance to get blocked by the browser's popup blocker and doesn't open the URL as a new window.
This function has to be run in response to a user interaction event, else the browser might reject it.

⚠️ This function needs to be run after the DOM has loaded (when using @run-at document-end or after DOMContentLoaded has fired).

Example - click to view

import { openInNewTab } from "@sv443-network/userutils";

document.querySelector("#my-button").addEventListener("click", () => {
  openInNewTab("https://example.org/");
});

interceptEvent()

Usage:

interceptEvent(
  eventObject: EventTarget,
  eventName: string,
  predicate?: (event: Event) => boolean
): void

Intercepts all events dispatched on the eventObject and prevents the listeners from being called as long as the predicate function returns a truthy value.
If no predicate is specified, all events will be discarded.
Calling this function will set the Error.stackTraceLimit to 1000 (if it's not already higher) to ensure the stack trace is preserved.

⚠️ This function should be called as soon as possible (I recommend using @run-at document-start), as it will only intercept events that are attached after this function is called.

Example - click to view

import { interceptEvent } from "@sv443-network/userutils";

interceptEvent(document.body, "click", (event) => {
  // prevent all click events on <a> elements within the entire <body>
  if(event.target instanceof HTMLAnchorElement) {
    console.log("Intercepting click event:", event);
    return true;
  }
  return false; // allow all other click events through
});

interceptWindowEvent()

Usage:

interceptWindowEvent(
  eventName: string,
  predicate?: (event: Event) => boolean
): void

Intercepts all events dispatched on the window object and prevents the listeners from being called as long as the predicate function returns a truthy value.
If no predicate is specified, all events will be discarded.
This is essentially the same as interceptEvent(), but automatically uses the unsafeWindow (or falls back to regular window).

⚠️ This function should be called as soon as possible (I recommend using @run-at document-start), as it will only intercept events that are attached after this function is called.
⚠️ In order for all events to be interceptable, the directive @grant unsafeWindow should be set.

Example - click to view

import { interceptWindowEvent } from "@sv443-network/userutils";

// prevent the pesky "Are you sure you want to leave this page?" popup
// as no predicate is specified, all events will be discarded by default
interceptWindowEvent("beforeunload");

isScrollable()

Usage:

isScrollable(element: Element): { horizontal: boolean, vertical: boolean }

Checks if an element has a horizontal or vertical scroll bar.
This uses the computed style of the element, so it will also work if the element is hidden.

Example - click to view

import { isScrollable } from "@sv443-network/userutils";

const element = document.querySelector("#element");
const { horizontal, vertical } = isScrollable(element);

console.log("Element has a horizontal scroll bar:", horizontal);
console.log("Element has a vertical scroll bar:", vertical);

observeElementProp()

Usage:

observeElementProp(
  element: Element,
  property: string,
  callback: (oldValue: any, newValue: any) => void
): void

This function observes changes to the given property of a given element.
While regular HTML attributes can be observed using a MutationObserver, this is not always possible for properties that are assigned on the JS object.
This function shims the setter of the provided property and calls the callback function whenever it is changed through any means.

When using TypeScript, the types for element, property and the arguments for callback will be automatically inferred.

Example - click to view

import { observeElementProp } from "@sv443-network/userutils";

const myInput = document.querySelector("input#my-input");

let value = 0;

setInterval(() => {
  value += 1;
  myInput.value = String(value);
}, 1000);


const observer = new MutationObserver((mutations) => {
  // will never be called:
  console.log("MutationObserver mutation:", mutations);
});

// one would think this should work, but "value" is a JS object *property*, not a DOM *attribute*
observer.observe(myInput, {
  attributes: true,
  attributeFilter: ["value"],
});


observeElementProp(myInput, "value", (oldValue, newValue) => {
  // will be called every time the value changes:
  console.log("Value changed from", oldValue, "to", newValue);
});

Math:

clamp()

Usage:

clamp(num: number, min: number, max: number): number

Clamps a number between a min and max boundary (inclusive).

Example - click to view

import { clamp } from "@sv443-network/userutils";

clamp(7, 0, 10);     // 7
clamp(-1, 0, 10);    // 0
clamp(5, -5, 0);     // 0
clamp(99999, 0, 10); // 10

// clamp without a min or max boundary:
clamp(-99999, -Infinity, 0); // -99999
clamp(99999, 0, Infinity);   // 99999

mapRange()

Usage:

mapRange(
  value: number,
  range1min: number,
  range1max: number,
  range2min: number,
  range2max: number
): number

Maps a number from one range to the spot it would be in another range.

Example - click to view

import { mapRange } from "@sv443-network/userutils";

mapRange(5, 0, 10, 0, 100); // 50
mapRange(5, 0, 10, 0, 50);  // 25

// to calculate a percentage from arbitrary values, use 0 and 100 as the second range
// for example, if 4 files of a total of 13 were downloaded:
mapRange(4, 0, 13, 0, 100); // 30.76923076923077

randRange()

Usages:

randRange(min: number, max: number): number
randRange(max: number): number

Returns a random number between min and max (inclusive).
If only one argument is passed, it will be used as the max value and min will be set to 0.

Example - click to view

import { randRange } from "@sv443-network/userutils";

randRange(0, 10);  // 4
randRange(10, 20); // 17
randRange(10);     // 7

randomId()

Usage:

randomId(length?: number, radix?: number): string

Generates a cryptographically strong random ID of a given length and radix (base).
Uses the Web Crypto API for generating the random numbers.
⚠️ This is not intended for generating encryption keys, only for generating IDs with a decent amount of entropy!

The default length is 16 and the default radix is 16 (hexadecimal).
You may change the radix to get digits from different numerical systems.
Use 2 for binary, 8 for octal, 10 for decimal, 16 for hexadecimal and 36 for alphanumeric.

Example - click to view

import { randomId } from "@sv443-network/userutils";

randomId();       // "1bda419a73629d4f" (length 16, radix 16)
randomId(10);     // "f86cd354a4"       (length 10, radix 16)
randomId(10, 2);  // "1010001101"       (length 10, radix 2)
randomId(10, 10); // "0183428506"       (length 10, radix 10)
randomId(10, 36); // "z46jfpa37r"       (length 10, radix 36)

Misc:

ConfigManager

Usage:

new ConfigManager(options: ConfigManagerOptions)

A class that manages a userscript's configuration that is persistently saved to and loaded from GM storage.
Also supports automatic migration of outdated data formats via provided migration functions.
You may create as many instances as you like as long as they have different IDs.

⚠️ The configuration is stored as a JSON string, so only JSON-compatible data can be used. Circular structures and complex objects will throw an error on load and save.
⚠️ The directives @grant GM.getValue and @grant GM.setValue are required for this to work.

The options object has the following properties:

Property	Description
`id`	A unique internal identification string for this configuration. If two ConfigManagers share the same ID, they will overwrite each other's data. Choose wisely because if it is changed, the previously saved data will not be able to be loaded anymore.
`defaultConfig`	The default config data to use if no data is saved in persistent storage yet. Until the data is loaded from persistent storage, this will be the data returned by `getData()`. For TypeScript, the type of the data passed here is what will be used for all other methods of the instance.
`formatVersion`	An incremental version of the data format. If the format of the data is changed in any way, this number should be incremented, in which case all necessary functions of the migrations dictionary will be run consecutively. Never decrement this number or skip numbers.
`migrations?`	(Optional) A dictionary of functions that can be used to migrate data from older versions of the configuration to newer ones. The keys of the dictionary should be the format version that the functions can migrate to, from the previous whole integer value. The values should be functions that take the data in the old format and return the data in the new format. The functions will be run in order from the oldest to the newest version. If the current format version is not in the dictionary, no migrations will be run.
`encodeData?`	(Optional, but required when decodeData is set) Function that encodes the data before saving - you can use compress() here to save space at the cost of a little bit of performance
`decodeData?`	(Optional, but required when encodeData is set) Function that decodes the data when loading - you can use decompress() here to decode data that was previously compressed with compress()

Methods:

loadData(): Promise<TData>
Asynchronously loads the configuration data from persistent storage and returns it.
If no data was saved in persistent storage before, the value of options.defaultConfig will be returned and written to persistent storage.
If the formatVersion of the saved data is lower than the current one and the options.migrations property is present, the data will be migrated to the latest format before the Promise resolves.

getData(): TData
Synchronously returns the current data that is stored in the internal cache.
If no data was loaded from persistent storage yet using loadData(), the value of options.defaultConfig will be returned.

setData(data: TData): Promise<void>
Writes the given data synchronously to the internal cache and asynchronously to persistent storage.

saveDefaultData(): Promise<void>
Writes the default configuration given in options.defaultConfig synchronously to the internal cache and asynchronously to persistent storage.

deleteConfig(): Promise<void>
Fully deletes the configuration from persistent storage.
The internal cache will be left untouched, so any subsequent calls to getData() will return the data that was last loaded.
If loadData() or setData() are called after this, the persistent storage will be populated with the value of options.defaultConfig again.
⚠️ If you want to use this method, the additional directive @grant GM.deleteValue is required.

Example - click to view

import { ConfigManager, compress, decompress } from "@sv443-network/userutils";

interface MyConfig {
  foo: string;
  bar: number;
  baz: string;
  qux: string;
}

/** Default config data */
const defaultConfig: MyConfig = {
  foo: "hello",
  bar: 42,
  baz: "xyz",
  qux: "something",
};
/** If any properties are added to, removed from or renamed in MyConfig, increment this number */
const formatVersion = 2;
/** Functions that migrate outdated data to the latest format - make sure a function exists for every previously used formatVersion and that no numbers are skipped! */
const migrations = {
  // migrate from format version 0 to 1
  1: (oldData: Record<string, unknown>) => {
    return {
      foo: oldData.foo,
      bar: oldData.bar,
      baz: "world",
    };
  },
  // asynchronously migrate from format version 1 to 2
  2: async (oldData: Record<string, unknown>) => {
    // arbitrary async operation required for the new format
    const qux = JSON.parse(await (await fetch("https://api.example.org/some-data")).text());
    return {
      foo: oldData.foo,
      bar: oldData.bar,
      baz: oldData.baz,
      qux,
    };
  },
};

const manager = new ConfigManager({
  /** A unique ID for this configuration - choose wisely as changing it is not supported yet! */
  id: "my-userscript",
  /** Default / fallback configuration data */
  defaultConfig,
  /** The current version of the script's config data format */
  formatVersion,
  /** Data format migration functions */
  migrations,

  // Compression example:
  // Adding this will save space at the cost of a little bit of performance while initially loading and saving the data
  // Only both of these properties or none of them should be set
  // Everything else will be handled by the ConfigManager instance
  /** Encode data using the "deflate-raw" algorithm and digests it as a base64 string */
  encodeData: (data) => compress(data, "deflate-raw", "base64"),
  /** Decode the "deflate-raw" encoded data as a base64 string */
  decodeData: (data) => decompress(data, "deflate-raw", "base64"),
});

/** Entrypoint of the userscript */
async function init() {
  // wait for the config to be loaded from persistent storage
  // if no data was saved in persistent storage before or getData() is called before loadData(), the value of options.defaultConfig will be returned
  // if the previously saved data needs to be migrated to a newer version, it will happen in this function call
  const configData = await manager.loadData();

  console.log(configData.foo); // "hello"

  // update the config
  configData.foo = "world";
  configData.bar = 123;

  // save the updated config - synchronously to the cache and asynchronously to persistent storage
  manager.saveData(configData).then(() => {
    console.log("Config saved to persistent storage!");
  });

  // the internal cache is updated synchronously, so the updated data can be accessed before the Promise resolves:
  console.log(manager.getData().foo); // "world"
}

init();

autoPlural()

Usage:

autoPlural(str: string, num: number | Array | NodeList): string

Automatically pluralizes a string if the given number is not 1.
If an array or NodeList is passed, the amount of contained items will be used.

Example - click to view

import { autoPlural } from "@sv443-network/userutils";

autoPlural("apple", 0); // "apples"
autoPlural("apple", 1); // "apple"
autoPlural("apple", 2); // "apples"

autoPlural("apple", [1]);    // "apple"
autoPlural("apple", [1, 2]); // "apples"

const items = [1, 2, 3, 4, "foo", "bar"];
console.log(`Found ${items.length} ${autoPlural("item", items)}`); // "Found 6 items"

pauseFor()

Usage:

pauseFor(ms: number): Promise<void>

Pauses async execution for a given amount of time.

Example - click to view

import { pauseFor } from "@sv443-network/userutils";

async function run() {
  console.log("Hello");
  await pauseFor(3000); // waits for 3 seconds
  console.log("World");
}

debounce()

Usage:

debounce(func: Function, timeout?: number): Function

Debounces a function, meaning that it will only be called once after a given amount of time.
This is very useful for functions that are called repeatedly, like event listeners, to remove extraneous calls.
All passed properties will be passed down to the debounced function.
The timeout will default to 300ms if left undefined.

Example - click to view

import { debounce } from "@sv443-network/userutils";

window.addEventListener("resize", debounce((event) => {
  console.log("Window was resized:", event);
}, 500)); // 500ms timeout

fetchAdvanced()

Usage:

fetchAdvanced(input: string | Request | URL, options?: {
  timeout?: number,
  // any other options from fetch() except for signal
}): Promise<Response>

A drop-in replacement for the native fetch() function that adds options like a timeout property.
The timeout will default to 10 seconds if left undefined. Set it to a negative number to disable the timeout.
Note that the signal option will be overwritten if passed.

Example - click to view

import { fetchAdvanced } from "@sv443-network/userutils";

fetchAdvanced("https://jokeapi.dev/joke/Any?safe-mode", {
  timeout: 5000,
  // also accepts any other fetch options like headers:
  headers: {
    "Accept": "text/plain",
  },
}).then(async (response) => {
  console.log("Fetch data:", await response.text());
}).catch((err) => {
  console.error("Fetch error:", err);
});

insertValues()

Usage:

insertValues(input: string, ...values: Stringifiable[]): string

Inserts values into a string in the format %n, where n is the number of the value, starting at 1.
The values will be stringified using toString() (see Stringifiable) before being inserted into the input string.
If not enough values are passed, the remaining placeholders will be left untouched.

Example - click to view

import { insertValues } from "@sv443-network/userutils";

insertValues("Hello, %1!", "World");                        // "Hello, World!"
insertValues("Hello, %1! My name is %2.", "World", "John"); // "Hello, World! My name is John."
insertValues("Testing %1", { toString: () => "foo" });      // "Testing foo"

// using an array for the values and not passing enough arguments:
const values = ["foo", "bar", "baz"];
insertValues("Testing %1, %2, %3 and %4", ...values); // "Testing foo, bar and baz and %4"

compress()

Usage:

compress(input: string | ArrayBuffer, compressionFormat: CompressionFormat, outputType?: "base64"): Promise<string>
compress(input: string | ArrayBuffer, compressionFormat: CompressionFormat, outputType: "arrayBuffer"): Promise<ArrayBuffer>

Compresses a string or ArrayBuffer using the specified compression format. Most browsers should support at least gzip and deflate
The outputType dictates which format the output will be in. It will default to base64 if left undefined.

⚠️ You need to provide the @grant unsafeWindow directive if you are using the base64 output type or you will get a TypeError.
⚠️ Not all browsers might support compression. Please check on this page for compatibility and supported compression formats.

Example - click to view

import { compress } from "@sv443-network/userutils";

// using gzip:

const fooGz = await compress("Hello, World!", "gzip");
const barGz = await compress("Hello, World!".repeat(20), "gzip");

// not as efficient with short strings but can save quite a lot of space with larger strings:
console.log(fooGz); // "H4sIAAAAAAAAE/NIzcnJ11EIzy/KSVEEANDDSuwNAAAA"
console.log(barGz); // "H4sIAAAAAAAAE/NIzcnJ11EIzy/KSVH0GJkcAKOPcmYEAQAA"

// depending on the type of data you might want to use a different compression format like deflate:

const fooDeflate = await compress("Hello, World!", "deflate");
const barDeflate = await compress("Hello, World!".repeat(20), "deflate");

// again, it's not as efficient initially but gets better with longer inputs:
console.log(fooDeflate); // "eJzzSM3JyddRCM8vyklRBAAfngRq"
console.log(barDeflate); // "eJzzSM3JyddRCM8vyklR9BiZHAAIEVg1"

decompress()

Usage:

decompress(input: string | ArrayBuffer, compressionFormat: CompressionFormat, outputType?: "string"): Promise<string>
decompress(input: string | ArrayBuffer, compressionFormat: CompressionFormat, outputType: "arrayBuffer"): Promise<ArrayBuffer>

Decompresses a string or ArrayBuffer that has been previously compressed using the specified compression format. Most browsers should support at least gzip and deflate
The outputType dictates which format the output will be in. It will default to string if left undefined.

⚠️ You need to provide the @grant unsafeWindow directive if you are using the string output type or you will get a TypeError.
⚠️ Not all browsers might support decompression. Please check on this page for compatibility and supported compression formats.

Example - click to view

import { compress, decompress } from "@sv443-network/userutils";

const compressed = await compress("Hello, World!".repeat(20), "gzip");

console.log(compressed); // "H4sIAAAAAAAAE/NIzcnJ11EIzy/KSVH0GJkcAKOPcmYEAQAA"

const decompressed = await decompress(compressed, "gzip");

console.log(decompressed); // "Hello, World!"

Arrays:

randomItem()

Usage:

randomItem(array: Array): any

Returns a random item from an array.
Returns undefined if the array is empty.

Example - click to view

import { randomItem } from "@sv443-network/userutils";

randomItem(["foo", "bar", "baz"]); // "bar"
randomItem([ ]);                   // undefined

randomItemIndex()

Usage:

randomItemIndex(array: Array): [item: any, index: number]

Returns a tuple of a random item and its index from an array.
If the array is empty, it will return undefined for both values.

Example - click to view

import { randomItemIndex } from "@sv443-network/userutils";

randomItemIndex(["foo", "bar", "baz"]); // ["bar", 1]
randomItemIndex([ ]);                   // [undefined, undefined]

// using array destructuring:
const [item, index] = randomItemIndex(["foo", "bar", "baz"]); // ["bar", 1]
// or if you only want the index:
const [, index] = randomItemIndex(["foo", "bar", "baz"]); // 1

takeRandomItem()

Usage:

takeRandomItem(array: Array): any

Returns a random item from an array and mutates the array by removing the item.
Returns undefined if the array is empty.

Example - click to view

import { takeRandomItem } from "@sv443-network/userutils";

const arr = ["foo", "bar", "baz"];
takeRandomItem(arr); // "bar"
console.log(arr);    // ["foo", "baz"]

randomizeArray()

Usage:

randomizeArray(array: Array): Array

Returns a copy of an array with its items in a random order.
If the array is empty, a new, empty array will be returned.

Example - click to view

import { randomizeArray } from "@sv443-network/userutils";

const foo = [1, 2, 3, 4, 5, 6];

console.log(randomizeArray(foo)); // [3, 1, 5, 2, 4, 6]
console.log(randomizeArray(foo)); // [4, 5, 2, 1, 6, 3]

console.log(foo); // [1, 2, 3, 4, 5, 6] - original array is not mutated

Translation:

This is a very lightweight translation function that can be used to translate simple strings.
Pluralization is not supported but can be achieved manually by adding variations to the translations, identified by a different suffix. See the example section of tr.addLanguage() for an example on how this might be done.

tr()

Usage:

tr(key: string, ...values: Stringifiable[]): string

The function returns the translation of the passed key in the language added by tr.addLanguage() and set by tr.setLanguage()
Should the translation contain placeholders in the format %n, where n is the number of the value starting at 1, they will be replaced with the respective item of the values rest parameter.
The items of the values rest parameter will be stringified using toString() (see Stringifiable) before being inserted into the translation.

If the key is not found or no language has been added or set before calling this function, it will return the key itself.
If the key is found and the translation contains placeholders but no values are passed, it will return the translation as-is, including unmodified placeholders.
If the key is found, the translation doesn't contain placeholders but values are still passed, they will be ignored and the translation will be returned as-is.

Example - click to view

import { tr } from "@sv443-network/userutils";

tr.addLanguage("en", {
  "welcome": "Welcome",
  "welcome_name": "Welcome, %1",
});
tr.addLanguage("de", {
  "welcome": "Willkommen",
  "welcome_name": "Willkommen, %1",
});

// this has to be called at least once before calling tr()
tr.setLanguage("en");

console.log(tr("welcome"));              // "Welcome"
console.log(tr("welcome_name", "John")); // "Welcome, John"
console.log(tr("non_existent_key"));     // "non_existent_key"

// language can be changed at any time, synchronously
tr.setLanguage("de");

console.log(tr("welcome"));              // "Willkommen"
console.log(tr("welcome_name", "John")); // "Willkommen, John"

tr.addLanguage()

Usage:

tr.addLanguage(language: string, translations: Record<string, string>): void

Adds a language and its associated translations to the translation function.
The passed language can be any unique identifier, though I recommend sticking to the ISO 639-1 standard.
The passed translations should be an object where the key is the translation key used in tr() and the value is the translation itself.
If tr.addLanguage() is called multiple times with the same language, the previous translations of that language will be overwritten.

The translation values may contain placeholders in the format %n, where n is the number of the value starting at 1.
These can be used to inject values into the translation when calling tr()

Example - click to view

import { tr } from "@sv443-network/userutils";

// add a language with associated translations:

tr.addLanguage("de", {
  "color": "Farbe",
});


// with placeholders:

tr.addLanguage("en", {
  "welcome_generic": "Welcome!",
  "welcome_name": "Welcome, %1!",
  "welcome_extended": "Welcome, %1!\nYour last login was on %2\nYou have %3 unread messages",
});


// can be used for different locales too:

tr.addLanguage("en-US", {
  "fries": "french fries",
});
tr.addLanguage("en-GB", {
  "fries": "chips",
});


// apply default values for different locales to reduce redundancy in shared translation values:

const translation_de = {
  "greeting": "Guten Tag!",
  "foo": "Foo",
};
tr.addLanguage("de-DE", translation_de);
tr.addLanguage("de-CH", {
  ...translation_de,
  // overwrite the "greeting" but keep other keys as they are
  "greeting": "Grüezi!",
});
tr.addLanguage("de-AT", {
  ...translation_de,
  // overwrite "greeting" again but keep other keys as they are
  "greeting": "Grüß Gott!",
});


// example for custom pluralization:

tr.addLanguage("en", {
  "items_added-0": "Added %1 items to your cart",
  "items_added-1": "Added %1 item to your cart",
  "items_added-n": "Added all %1 items to your cart",
});

/** Returns the custom pluralization identifier for the given number of items (or size of Array/NodeList) */
function pl(num: number | unknown[] | NodeList) {
  if(typeof num !== "number")
    num = num.length;

  if(num === 0)
    return "0";
  else if(num === 1)
    return "1";
  else
    return "n";
};

const items = [];
tr(`items_added-${pl(items)}`, items.length); // "Added 0 items to your cart"

items.push("foo");
tr(`items_added-${pl(items)}`, items.length); // "Added 1 item to your cart"

items.push("bar");
tr(`items_added-${pl(items)}`, items.length); // "Added all 2 items to your cart"

tr.setLanguage()

Usage:

tr.setLanguage(language: string): void

Synchronously sets the language that will be used for translations.
No validation is done on the passed language, so make sure it is correct and it has been added with tr.addLanguage() before calling tr()

For an example, see tr()

tr.getLanguage()

Usage:

tr.getLanguage(): string | undefined

Returns the currently active language set by tr.setLanguage()
If no language has been set yet, it will return undefined.

Utility types:

UserUtils also offers some utility types that can be used in TypeScript projects.
They don't alter the runtime behavior of the code, but they can be used to make the code more readable and to prevent errors.

Stringifiable

This type describes any value that either is a string itself or can be converted to a string.
To be considered stringifiable, the object needs to have a toString() method that returns a string (all primitive types have this method).
This method allows not just explicit conversion by calling it, but also implicit conversion by passing it into the String() constructor or by interpolating it in a template string.

Example - click to view

import type { Stringifiable } from "@sv443-network/userutils";

function logSomething(value: Stringifiable) {
  console.log(`Log: ${value}`); // implicit conversion using `value.toString()`
}

const fooObject = {
  toString: () => "hello world",
};

const barObject = {
  baz: "",
};

logSomething("foo");     // "Log: foo"
logSomething(42);        // "Log: 42"
logSomething(true);      // "Log: true"
logSomething({});        // "Log: [object Object]"
logSomething(Symbol(1)); // "Log: Symbol(1)"
logSomething(fooObject); // "Log: hello world"

logSomething(barObject); // Type Error

NonEmptyArray

Usage:

NonEmptyArray<TItem = unknown>

This type describes an array that has at least one item.
Use the generic parameter to specify the type of the items in the array.

Example - click to view

import type { NonEmptyArray } from "@sv443-network/userutils";

function logFirstItem(array: NonEmptyArray<string>) {
  console.log(parseInt(array[0]));
}

function somethingElse(array: NonEmptyArray) {
  // array is typed as NonEmptyArray<unknown> when not passing a
  // generic parameter, so this throws a TS error:
  console.log(parseInt(array[0])); // Argument of type 'unknown' is not assignable to parameter of type 'string'
}

logFirstItem(["04abc", "69"]); // 4

NonEmptyString

Usage:

NonEmptyString<TString extends string>

This type describes a string that has at least one character.

Example - click to view

import type { NonEmptyString } from "@sv443-network/userutils";

function convertToNumber<T extends string>(str: NonEmptyString<T>) {
  console.log(parseInt(str));
}

convertToNumber("04abc"); // "4"
convertToNumber("");      // type error: Argument of type 'string' is not assignable to parameter of type 'never'

LooseUnion

Usage:

LooseUnion<TUnion extends string | number | object>

A type that offers autocomplete in the IDE for the passed union but also allows any value of the same type to be passed.
Supports unions of strings, numbers and objects.

Example - click to view

function foo(bar: LooseUnion<"a" | "b" | "c">) {
  console.log(bar);
}

// when typing the following, autocomplete suggests "a", "b" and "c"
// foo("

foo("a"); // included in autocomplete, no type error
foo("");  // *not* included in autocomplete, still no type error
foo(1);   // type error: Argument of type '1' is not assignable to parameter of type 'LooseUnion<"a" | "b" | "c">'

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UserUtils

Table of Contents:

Installation:

Preamble:

License:

Features:

DOM:

SelectorObserver

Methods:

Basic usage:

Get and remove listeners:

Chaining:

getUnsafeWindow()

insertAfter()

addParent()

addGlobalStyle()

preloadImages()

openInNewTab()

interceptEvent()

interceptWindowEvent()

isScrollable()

observeElementProp()

Math:

clamp()

mapRange()

randRange()

randomId()

Misc:

ConfigManager

Methods:

autoPlural()

pauseFor()

debounce()

fetchAdvanced()

insertValues()

compress()

decompress()

Arrays:

randomItem()

randomItemIndex()

takeRandomItem()

randomizeArray()

Translation:

tr()

tr.addLanguage()

tr.setLanguage()

tr.getLanguage()

Utility types:

Stringifiable

NonEmptyArray

NonEmptyString

LooseUnion