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object.watch

Observe changes on object properties.

Tento skript by neměl být instalován přímo. Jedná se o knihovnu, kterou by měly jiné skripty využívat pomocí meta příkazu // @require https://update.greasyfork.org/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;
        }
    });
}