文章结构

　　生成器函数的定义与使用

　　给生成器函数传参

　　给生成器函数异步传参

　　生成器函数的应用场景

　　　　解决回调地域

 1  //生成器函数的定义与使用
 2         function *fn(){
 3             //yield类似于断电
 4             console.log(111);
 5             yield `第一段`
 6             console.log(222);
 7             yield `第二段`
 8             console.log(333);
 9             yield `第三段`
10             console.log(444);
11         }
12 
13         //调用
14         let iterator = fn();
15         //每次调用next会执行生成器函数中yield段代码，并且返回包含yield的值的对象
16         console.log(iterator.next());
17         console.log(iterator.next());
18         console.log(iterator.next());
19         console.log(iterator.next());
20 
21         for(let i of fn()){
22             console.log(i);
23         }

给生成器函数传参

 1        function * fn(arg){
 2         console.log(arg);
 3         let one = yield 1;
 4         console.log(one);
 5         let two = yield 2;
 6         console.log(two);
 7         let three = yield 3;
 8         console.log(three);
 9        }
10 
11        //执行获取迭代器对象
12        let iterator = fn('AAA');
13        iterator.next();
14        //从第二次开始next的参数会成为yield的返回值
15        iterator.next('BBB');
16        iterator.next('CCC');
17        iterator.next('DDD');

给生成器函数异步传参

 1 function getname() {
 2     setTimeout(() => {
 3         let name = 'zhangsan';
 4         iterator.next(name);
 5     }, 1000)
 6 }
 7 
 8 function getdata() {
 9     setTimeout(() => {
10         let data = 'data';
11         iterator.next(data);
12     }, 2000)
13 }
14 
15 function gettime() {
16     setTimeout(() => {
17         let time = 'time';
18         iterator.next(time);
19     }, 3000)
20 }
21 
22 function* fn() {
23     getname();
24     // 可以使用一个变量去接收yield的返回值，yield返回上一次调用iterator.next()的参数
25     let one = yield;
26     console.log(one);
27     getdata();
28     let two = yield;
29     console.log(two);
30     gettime();
31     let three = yield;
32     console.log(three);
33 }
34 
35 let iterator = fn();
36 iterator.next();

生成器函数的应用场景

解决回调地域

 1 setTimeout(() => {
 2             console.log(111);
 3             setTimeout(() =>{
 4                 console.log(222);
 5                 setTimeout(()=>{
 6                     console.log(333)
 7                 },3000)
 8             },2000)
 9         },1000)
10 
11         function fn1(){
12             setTimeout(()=>{
13                 console.log(111);
14                 iterator.next();
15             },1000)
16         }
17 
18         function fn2(){
19             setTimeout(()=>{
20                 console.log(222);
21                 iterator.next();
22             },1000)
23         }
24 
25         function fn3(){
26             setTimeout(()=>{
27                 console.log(333);
28                 iterator.next();
29             },1000)
30         }
31 
32         function *fn(){
33             fn1();
34             yield;
35             fn2();
36             yield;
37             fn3();
38             yield;
39         }
40 
41         let iterator = fn();
42         iterator.next();