Do I can Symbol.iterator in Object by prototype?"JavaScript"-CodePudding

Why I can't add Symbol.iterator into Object like that

Object.prototype[Symbol.iterator];

let obj = {num: 1 , type : ' :) '}
for (let p of obj) {
  console.log(p);
}
// TypeError: obj is not iterable

CodePudding user response：

You have to assign a generator function to Object.prototype[Symbol.iterator].

Object.prototype[Symbol.iterator] = function*() {
  for (let k in this) {
    yield this[k];
  }
};

let obj = {
  num: 1,
  type: ' :) '
}
for (let p of obj) {
  console.log(p);
}

CodePudding user response：

Because you didnt actually assign anything to Object.prototype[Symbol.iterator] - if you do assign an iterator function that does somethign sensible I think it might work as you expected

Object.prototype[Symbol.iterator] = function*(){
  for(let entry of Object.entries(this))
     yield entry
};

let obj = {num: 1 , type : ' :) '}
for (let [k,v] of obj) {
  console.log(k,v);
}

// another way
console.log(...obj)