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object.watch

Observe changes on object properties

Fra og med 26.09.2014. Se den nyeste version.

Dette script bør ikke installeres direkte. Det er et bibliotek, som andre scripts kan inkludere med metadirektivet // @require https://update.greasyfork.org/scripts/5314/18909/objectwatch.js 

// ==UserScript==
// @name        object.watch
// @namespace   object.prototype.watch_and_object.prototype.unwatch
// @description Observe changes on object properties
// ==/UserScript==

/*
    * object.watch polyfill
    *
    * 2012-04-03
    *
    * By Eli Grey, http://eligrey.com
    * Public Domain.
    * NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
    *
*/

// object.watch
if (!Object.prototype.watch) {
    Object.defineProperty(Object.prototype, "watch", {
        enumerable: false,
        configurable: true,
        writable: false,
        value: function(prop, handler) {
            var oldval = this[prop],
                newval = oldval,
                getter = function() {
                    return newval;
                },
                setter = function(val) {
                    oldval = newval;
                    return newval = handler.call(this, prop, oldval, val);
                };
            if (delete this[prop]) { // can't watch constants
                Object.defineProperty(this, prop, {
                    get: getter,
                    set: setter,
                    enumerable: true,
                    configurable: true
                });
            }
        }
    });
}

// object.unwatch
if (!Object.prototype.unwatch) {
    Object.defineProperty(Object.prototype, "unwatch", {
        enumerable: false,
        configurable: true,
        writable: false,
        value: function(prop) {
            var val = this[prop];
            delete this[prop]; // remove accessors
            this[prop] = val;
        }
    });
}