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9gag - Scroll down to current position (local)

Scroll down back where the focus was when you clicked the arrow-up icon or scrolled up

当前为 2023-06-21 提交的版本，查看 最新版本。

  1. // ==UserScript==
  2. // @name         9gag - Scroll down to current position (local)
  3. // @namespace    https://github.com/Procyon-b
  4. // @version      0.3
  5. // @description  Scroll down back where the focus was when you clicked the arrow-up icon or scrolled up
  6. // @author       Achernar
  7. // @match        https://9gag.com/*
  8. // @grant        none
  9. // ==/UserScript==
  10.  
  11. (function() {
  12. "use strict";
  13.  
  14. var pos=[0,0], allPos={}, L, btt=document.querySelector('.back-to-top')
  15.  
  16. if (!btt) return;
  17.  
  18. window.addEventListener('scroll', savePos);
  19.  
  20. function savePos() {
  21.   var d=window.scrollY - pos[1];
  22.   if (d < 0) showHide(true);
  23.   if (d >= 0) {
  24.     pos[0]=window.scrollX;
  25.     pos[1]=window.scrollY;
  26.     showHide();
  27.     }
  28.   }
  29.  
  30. function showHide(show=false) {
  31.   if (show == L.disp) return;
  32.   back.style.display= show?'':'none';
  33.   L.disp=show;
  34.   }
  35.  
  36. var back=document.createElement('a');
  37.  
  38. document.querySelector('header#top-nav').appendChild(back);
  39.  
  40. back.href='javascript:;';
  41. back.classList='back-to-top';
  42. back.style='transform: rotate(180deg); top: 5em; display: none;';
  43. back.title='Scroll back to position';
  44.  
  45. back.addEventListener('click', function(e){
  46.   if (pos) window.scrollTo.apply(null, pos);
  47.   showHide();
  48.   });
  49.  
  50. var hRS=history.replaceState;
  51.  
  52. history.replaceState=function() {
  53.   setTimeout(LocPos, 0);
  54.   // unlink "pos" "L"
  55.   pos=[0,0];
  56.   L={disp:false};
  57.   return hRS.apply(history, arguments);
  58.   }
  59.  
  60. function LocPos() {
  61.   if (!allPos[location.href]) allPos[location.href]={pos:[0,0], disp:false};
  62.   L=allPos[location.href];
  63.   pos=L.pos;
  64.   back.style.display= L.disp ? '':'none';
  65.   }
  66.  
  67. LocPos();
  68.  
  69. })();