Symbol »ù±¾Ó÷¨¡ª¡ª×Ô¶¨Òåfor...ofÑ­»·

var o = new Object

o[Symbol.iterator] = function() {
    var v = 0
    return {
        next: function() {
            return { value: v++, done: v > 10 }
        }
    }        
};

for(var v of o) 
    console.log(v); // 0 1 2 3 ... 9