auto amazon of tampermonkey script

auto-amazon.js

// ==UserScript==
// @name         auto-amazon
// @namespace    http://tampermonkey.net/auto-amazon
// @version      0.1
// @description  auto-amazon
// @author       DebugMi
// @match        https://www.amazon.cn/*
// @grant        GM_log
// @grant        GM_setValue
// @grant        GM_getValue
// @grant        GM_deleteValue
// @grant        GM_listValues
// @run-at document-end
// ==/UserScript==

;(function () {
  'use strict'
  // search word
  const searchWord = '机械键盘'
  // find a word then click it
  const findKeyWord = '斐尔克'
  // result list scroll count
  const listScrollCount = 5
  // detail page scroll count
  const detailScrollCount = 10
  // to link after finish work
  const homePage = 'https://www.amazon.cn/'

  main()

  function main() {
    const task = getTask() || 'search'
    log(`start, task is ${task}`)
    switch (task) {
      case 'search':
        handleSearch()
        break
      case 'findItem':
        handleFindItem()
        break
      case 'detailPage':
        handleDetailPage()
        break
      case 'end':
        handleEnd()
        break
      default:
        break
    }
  }

  function handleSearch() {
    sleep(3000).then(() => {
      log('start search')
      const $input = $('#twotabsearchtextbox')
      const $submit = $('form.nav-searchbar')
      changeTask('findItem')
      $input.value = searchWord
      $submit.submit()
    })
  }

  function handleFindItem() {
    randomScroll(listScrollCount, 0, () => {
      const $item = $('.s-result-item[data-component-type]', true)[0]
      const itemUrl = $item.querySelector('.s-product-image-container a').href
      changeTask('detailPage')
      location.assign(itemUrl)
    })
  }

  function handleDetailPage() {
    randomScroll(detailScrollCount, 0, () => {
      window.scrollTo(0, random(0, 100))
      sleep(random(0, 2000)).then(() => {
        changeTask('end')
        $('#add-to-cart-button').click()
      })
    })
  }

  function handleEnd() {
    sleep(random(1000, 3000)).then(() => {
      changeTask('search')
      location.assign(homePage)
    })
  }

  function scroll(num) {
    window.scrollBy(0, num)
  }

  function randomScroll(totalCount, curCount, cb) {
    if (curCount > totalCount) {
      return cb()
    }
    log(`scrolling...${totalCount}...${curCount}`)
    return sleep(random(0, 3000)).then(() => {
      scroll(random(0, 500))
      return randomScroll(totalCount, curCount + 1, cb)
    })
  }

  function random(min, max) {
    min = Math.ceil(min)
    max = Math.floor(max)
    return Math.floor(Math.random() * (max - min) + min)
  }

  function $(selector, isAll) {
    if (isAll) {
      return document.querySelectorAll(selector)
    }
    return document.querySelector(selector)
  }

  function log(str) {
    GM_log(str)
  }

  function getCache(key) {
    return GM_getValue(key)
  }

  function setCache(key, value) {
    return GM_setValue(key, value)
  }

  function removeCache(key) {
    return GM_deleteValue(key)
  }

  function changeTask(nextTask) {
    setCache('mi-task', nextTask)
  }

  function getTask() {
    return getCache('mi-task')
  }

  function sleep(time) {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        resolve('')
      }, time)
    })
  }
})()