ES6 generator and yield keyword

One, the generator (generator)

The shape function* () { }of the function generator function

Two, yield keywords

1. yield Keyword should be used with generator
2. Builder yieldrole similar return, returns an Generatorobject ( Generatoressentially a special Iterator).

   function* generatorFunc() {
         
         
   	let arr = [1, 2];
   	for(let i=0; i<arr.length; i++){
         
         
   		yield arr[i];
   	}
   }
   let gn = generatorFunc();
   gn.next();	// {value: 1, done: false}
   gn.next();	// {value: 2, done: false}
   gn.next();	// {value: undefined, done: true}
   // 或者使用 for...of 遍历生成器
   

3. next() Method to pass value to function

   function* generatorFunc2(_a) {
         
         
   	let x = 2 * (yield _a + 1);
   	console.log(`x的值为：${
           
           x}`);
   	let y = 7 + (yield x)
   	console.log(`y的值为：${
           
           y}`);
   	yield y
   }
   let gn = generatorFunc2(5);
   gn.next();	// {value: 6, done: false}
   gn.next(5);	// {value: 10, done: false} 
   // x的值为：10
   gn.next(4);	// {value: 11, done: false}
   // y的值为：11
   gn.next();	// {value: undefined, done: true}
   

4. Used in the generator return

   function* generatorFunc3() {
         
         
   	let arr = [1, 2];
   	for(let i=0; i<arr.length; i++){
         
         
   		yield arr[i];
   	}
   	return 'done';
   	return 'done2';
   }
   let gn = generatorFunc3();
   gn.next();	// {value: 1, done: false}
   gn.next();	// {value: 2, done: false}
   gn.next();	// {value: 'done', done: true}
   gn.next();	// {value: undefined, done: true}