☰

object.watch

Observe changes on object properties.

This script should not be not be installed directly. It is a library for other scripts to include with the meta directive // @require https://update.greatest.deepsurf.us/scripts/5314/20683/objectwatch.js 

  1. /*
  2.     * object.watch polyfill
  3.     *
  4.     * 2012-04-03
  5.     *
  6.     * By Eli Grey, http://eligrey.com
  7.     * Public Domain.
  8.     * NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
  9.     *
  10. */
  11.  
  12. // object.watch
  13. if (!Object.prototype.watch) {
  14.     Object.defineProperty(Object.prototype, "watch", {
  15.         enumerable: false,
  16.         configurable: true,
  17.         writable: false,
  18.         value: function(prop, handler) {
  19.             var oldval = this[prop],
  20.                 newval = oldval,
  21.                 getter = function() {
  22.                     return newval;
  23.                 },
  24.                 setter = function(val) {
  25.                     oldval = newval;
  26.                     return newval = handler.call(this, prop, oldval, val);
  27.                 };
  28.             if (delete this[prop]) { // can't watch constants
  29.                 Object.defineProperty(this, prop, {
  30.                     get: getter,
  31.                     set: setter,
  32.                     enumerable: true,
  33.                     configurable: true
  34.                 });
  35.             }
  36.         }
  37.     });
  38. }
  39.  
  40. // object.unwatch
  41. if (!Object.prototype.unwatch) {
  42.     Object.defineProperty(Object.prototype, "unwatch", {
  43.         enumerable: false,
  44.         configurable: true,
  45.         writable: false,
  46.         value: function(prop) {
  47.             var val = this[prop];
  48.             delete this[prop]; // remove accessors
  49.             this[prop] = val;
  50.         }
  51.     });
  52. }