[AnkhMorporkian]

This is huge.

        var proto = new Proxy({}, {
            get(target, propertyKey, receiver) {
            console.log('GET '+propertyKey);
            return target[propertyKey];
         }});

I've been following ES6 pretty closely, but somehow I missed this huge feature. Don't get me wrong, I love generators and destructuring, but this is soooo cool.

[tracker1]

Should allow for the creation of a library to support Functional JS immutable instances...

[Offler]

Getters have been in JS since ES5 and can do what you just wrote. Obv Proxy is more powerful/has more traps.

[rauschma]

Not completely: with getters, you have to decide on a specific set of properties, the proxy GET trap intercepts all get operations. But I agree that you don’t always need proxies.