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Extended SPACE Key Page Scroller

By default the SPACE key scrolls the page down by full height of browser view. With this script, pressing SHIFT+SPACE will scroll half of the view height. Page scroll by a quarter view height can be done using either LEFTSHIFT+RIGHTSHIFT+SPACE or SHIFT+CAPSLOCK+SPACE (configurable via variable).

  1. // ==UserScript==
  2. // @name         Extended SPACE Key Page Scroller
  3. // @namespace    ExtendedSpaceKeyPageScroller
  4. // @version      1.0.3
  5. // @description  By default the SPACE key scrolls the page down by full height of browser view. With this script, pressing SHIFT+SPACE will scroll half of the view height. Page scroll by a quarter view height can be done using either LEFTSHIFT+RIGHTSHIFT+SPACE or SHIFT+CAPSLOCK+SPACE (configurable via variable).
  6. // @author       jcunews
  7. // @match        *://*/*
  8. // @grant        none
  9. // @run-at       document-start
  10. // ==/UserScript==
  11.  
  12.  
  13. // *** Configuration Start ***
  14.  
  15. // QuarterScrollKey: Determine what key combination to use for scrolling page by a quarter height of view.
  16. // 0      = Use both SHIFT keys. i.e. LeftShift+RightShift+Space
  17. // 1/else = Use CAPSLOCK key. i.e. Shift+CapsLock+Space
  18. var QuarterScrollKey = 1;
  19.  
  20. // *** Configuration End ***
  21.  
  22.  
  23. var shiftKeys = 0, capsLock = false;
  24.  
  25. addEventListener("keydown", function(ev) {
  26.   switch (ev.which) {
  27.     case 16: //SHIFT
  28.       shiftKeys |= ev.location;
  29.       break;
  30.     case 20: //CAPSLOCK
  31.       capsLock = true;
  32.   }
  33. }, true);
  34.  
  35. addEventListener("keyup", function(ev) {
  36.   switch (ev.which) {
  37.     case 16: //SHIFT
  38.       shiftKeys &= ~ev.location;
  39.       break;
  40.     case 20: //CAPSLOCK
  41.       capsLock = false;
  42.   }
  43. }, true);
  44.  
  45. addEventListener("keypress", function(ev, delta) {
  46.   if (!ev.shiftKey) {
  47.     shiftKeys = 0;
  48.   } else if (!shiftKeys) {
  49.     shiftKeys = 1;
  50.   }
  51.   if ((ev.which === 32) && !ev.altKey && (["INPUT", "TEXTAREA"].indexOf(document.activeElement.tagName) < 0)) {
  52.     if (((shiftKeys === 3) && !capsLock && !QuarterScrollKey) || //with both SHIFT key
  53.         (shiftKeys && (shiftKeys < 3) && capsLock && QuarterScrollKey)) { //with SHIFT+CAPSLOCK key
  54.       delta = 4;
  55.     } else if (shiftKeys) { //with one SHIFT key
  56.       delta = 2;
  57.     } else delta = 0;
  58.     if (delta) {
  59.       scrollBy(0, innerHeight / delta);
  60.       ev.preventDefault();
  61.       ev.stopPropagation();
  62.       ev.stopImmediatePropagation();
  63.     }
  64.   }
  65. }, true);