再次学习 Iterator 迭代器 与 Generator 生成器

Iterator :

返回的结果是:{value, done}

function chef(foods){

let i = 0;

return {

next(){

let done = ( i> foods.length);

           let value = !done? foods[i++]:undefined

return{

value,

done

}

}

}

}

let wanghao = chef(['西红柿','鸡蛋'])

console.log(wanghao.next());

console.log(wanghao.next());

...

generator(生成器):

function* chef()

{

yeild '西红柿';

yeild '鸡蛋';

}

let wanghao = chef();

改造下:

function* chef(foods){

for(var i =0;i<foods.length;i++)

{

yeild foods[i]

}

}

var wanghao = chef(['西红柿','鸡蛋'])

console.log(wanghao.next());

console.log(wanghao.next());

...

用class生成的Iterator:

class chef {

constructor(arr) {

this.foods = arr

this.i = 0;

}

next() {

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

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

return {

value,

done

}

}

}

var a = new chef([1, 2, 3]);

console.log(a.next());

console.log(a.next());

console.log(a.next());

console.log(a.next());

console.log(a.next());