"JavaScript" ES6 new syntax

function* statement

The function* declaration (the Function keyword followed by an asterisk) defines a generator (generator) function that returns a generator object.

A generator is a function that you can exit from and then re-enter. The environment of the generator (the bound variable) is saved after each execution and continues to be used the next time it is entered.

Invoking a generator function does not immediately execute its body, but instead returns an iterator (iterator) object for the generator function. When an expression of this iterator next()方法被调用时，生成器函数的主体会被执行直至第一个 yield , the expression defines the value returned by the iterator, or is yield* delegated to another generator function. next()方法返回一个对象，该对象有一个the Value property, which represents产出的值，和一个done属性，表示生成器是否已经产出了它最后的值。

Yield

function* Idmaker () {  var index = 0;  while (index<3)    yield index++;} var Gen = Idmaker (); Console.log (Gen.next (). value); 0console.log (Gen.next (). value); 1console.log (Gen.next (). value); 2console.log (Gen.next (). value); Undefined

yield*

function* Anothergenerator (i) {  yield i + 1;  Yield i + 2;  Yield i + 3;} function* Generator (i) {  yield i;  yield* Anothergenerator (i);  Yield i + 10;} var gen = generator; Console.log (Gen.next (). value); 10console.log (Gen.next (). value); 11console.log (Gen.next (). value); 12console.log (Gen.next (). value); 13console.log (Gen.next (). value); 20

　　

"JavaScript" ES6 new syntax