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Mouse wheel event

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  1. /*
  2.  * Author URL: http://adomas.org/javascript-mouse-wheel/
  3.  */
  4.  
  5. /** This is high-level function.
  6.  * It must react to delta being more/less than zero.
  7.  */
  8. function handle(delta) {
  9.         if (delta < 0)
  10. 		…;
  11.         else
  12. 		…;
  13. }
  14.  
  15. /** Event handler for mouse wheel event.
  16.  */
  17. function wheel(event){
  18.         var delta = 0;
  19.         if (!event) /* For IE. */
  20.                 event = window.event;
  21.         if (event.wheelDelta) { /* IE/Opera. */
  22.                 delta = event.wheelDelta/120;
  23.                 /** In Opera 9, delta differs in sign as compared to IE.
  24.                  */
  25.                 if (window.opera)
  26.                         delta = -delta;
  27.         } else if (event.detail) { /** Mozilla case. */
  28.                 /** In Mozilla, sign of delta is different than in IE.
  29.                  * Also, delta is multiple of 3.
  30.                  */
  31.                 delta = -event.detail/3;
  32.         }
  33.         /** If delta is nonzero, handle it.
  34.          * Basically, delta is now positive if wheel was scrolled up,
  35.          * and negative, if wheel was scrolled down.
  36.          */
  37.         if (delta)
  38.                 handle(delta);
  39. }
  40.  
  41. /** Initialization code. 
  42.  * If you use your own event management code, change it as required.
  43.  */
  44. if (window.addEventListener)
  45.         /** DOMMouseScroll is for mozilla. */
  46.         window.addEventListener('DOMMouseScroll', wheel, false);
  47. /** IE/Opera. */
  48. window.onmousewheel = document.onmousewheel = wheel;

URL: http://adomas.org/javascript-mouse-wheel/

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