如何让一个普通的对象变得可枚举

var obj = {
    a: 2,
    b: 3
};

Object.defineProperty(obj, Symbol.iterator, {
    enumerable: false,
    writable: false,
    configurable: true,
    value: function() {
        var self = this;
        idx = 0;
        var ks = Object.keys( self );
        console.log(ks)
        return {
            next: function() {
                return {
                    value: self[ks[idx++]],
                    done: (idx > ks.length)
                }
                
            }
        }
    }
})


for(let v of obj) {
    console.log(v);
}