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object.watch

Observe changes on object properties.

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greatest.deepsurf.us/scripts/5314/20683/objectwatch.js 

/*
    * 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;
        }
    });
}