Amazon CPU Tamer

It reduces CPU usage on Amazon shopping pages. Enjoy your snappy shopping.

Fra 18.11.2020. Se den seneste versjonen.

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name        Amazon CPU Tamer
// @name:ja     Amazon CPU Tamer
// @name:zh-CN  Amazon CPU Tamer
// @namespace   knoa.jp
// @contributionURL https://paypal.me/kantankikaku
// @description It reduces CPU usage on Amazon shopping pages. Enjoy your snappy shopping.
// @description:ja AmazonのショッピングページでのCPU使用率を削減します。お買いものをサクサク楽しみましょう。
// @description:zh-CN 减少Amazon购物页面上的CPU利用率。顺利地享受买东西吧。
// @include     https://www.amazon.com/*
// @include     https://www.amazon.co.jp/*
// @include     https://www.amazon.*
// @exclude     */cart/*
// @exclude     */buy/*
// @version     1.2.3
// @grant       none
// @run-at      document-start
// ==/UserScript==

/*
[update] 1.2.3
Add a UK associate ID.

*/
(function(){
  const SCRIPTNAME = 'Amazon Cpu Tamer';
  console.log(SCRIPTNAME);
  const TAMEDINTERVAL = 60*1000;/* a bunch of intervals does cost so much even if the processes do nothing */
  const QUICKRESPONSE =  1*1000;/* some of the interactions need rather quick response such as video guides */
  /* tame quick intervals */
  window.originalSetInterval = window.setInterval;
  window.setInterval = function(f, interval, ...args){
    if(interval < TAMEDINTERVAL){
      console.log(SCRIPTNAME, 'interval:', interval, 'to', TAMEDINTERVAL);
      interval = TAMEDINTERVAL;
      window.setTimeout(f, QUICKRESPONSE, ...args);
    }
    return window.originalSetInterval(f, interval, ...args);
  };
  /* add an associate tag */
  switch(location.host){
    case('www.amazon.com'):
      addTag('knoa-20');
      break;
    case('www.amazon.co.uk'):
      addTag('knoa-21');
      break;
    case('www.amazon.co.jp'):
      addTag('knoa-22');
      break;
  }
  function addTag(tag){
    const url = new URL(location.href);
    if(url.searchParams.get('tag') !== null) return;/* do not overwrite */
    console.log(SCRIPTNAME, 'associate tag:', tag);
    document.documentElement.addEventListener('mousedown', function(e){
      for(let target = e.target; target; target = target.parentNode){
        if(target.href && target.href.startsWith(location.origin)){
          const separator = (target.href.includes('?')) ? '&' : '?';
          target.href = target.href + separator + 'tag=' + tag;
        }
      }
    });
    const separator = (url.search === '') ? '?' : '&';
    history.replaceState(null, document.title, location.href + separator + 'tag=' + tag);
  }
})();