PainScroll

README.md

Le Script

Tested with ViolentMonkey on Firefox

Script is buggy, but that makes it better I guess

painscroll.user.js

// ==UserScript==
// @name        PainScroll
// @copyright   Made by @[email protected]
// @author      Kura
// @description Scrolling made more painful. And rewarding?
// @version     1.0
// @namespace   z0ne
// @match       *://*/*
// @downloadURL https://gist.github.com/cking/f14c4d5302d1a982b08b3f9ba8a8bc26/raw/painscroll.user.js
// @homepageURL https://gist.github.com/cking/f14c4d5302d1a982b08b3f9ba8a8bc26
// @grant       GM_setValue
// @grant       GM_getValue
// ==/UserScript==

function rand(min, max) {  const rounds = parseInt(Math.random() * 10)
  let rnd = Math.random()
  for (let i = 0; i <= rounds; i++) {
    rnd += Math.random()
  }
  rnd -= parseInt(rnd)

  min = min || 0
  max = max || 1
  const v = rnd  * (max - min) + min
  if (max <= 1) {
    return v
  }

  return parseInt(v)
}

function chance(min) {
  return rand() > min
}

let lastPosition = {
  x: 0,
  y: 0
}

function onScroll(ev) {
  const offset = {
    x: lastPosition.x - ev.pageX,
    y: lastPosition.y - ev.pageY
  }

  lastPosition.x = ev.pageX
  lastPosition.y = ev.pageY

  if (!chance(0.75)) {
    return
  }

  const x = jumpScroll(offset.x)
  const y = jumpScroll(offset.y)

  window.scrollBy(x, y)
}

function jumpScroll(offset) {
  if (offset == 0) {
    return 0
  }

  if (chance(0.25)) {
    return 0
  }

  let modifier = chance(0.66) ? 1 : -1
  modifier *= rand(0, 32)

  return offset * modifier
}

document.addEventListener("DOMMouseScroll", onScroll)
document.addEventListener("mousewheel",     onScroll)