symbol,iterator,generator （二）

Iterator :

 返回的结果是:{value, done}

 

 

写一个基于class的Iterator:

class MyIterator {

 

constructor(arr) {

   this.arr = arr

   this.i = 0;

}

next() {

    let done = (this.i >= this.arr.length)

    let value = !done ? this.arr[this.i++] : undefined

    return {

        value,

        done }

     

     }

}

var iterator = new MyIterator([1, 2, 3]);

console.log(iterator.next());

console.log(iterator.next());

console.log(iterator.next());

console.log(iterator.next());

console.log(iterator.next());