6.generator

• 只用调用next时才可以调用；
• 必须先给generator 函数赋值
• next 的时候会用value,done两个参数，done为true表示没有下个yield了；

/**
 *generator
 */
function* dosomething():any{
    console.log(1); // 1
    yield 3;
    console.log(2); // 2
}
let dosome:any = dosomething();
let val1:any = dosome.next();
let val2:any = dosome.next();
console.log(val1); // { value: 3, done: false }
console.log(val2); //{ value: undefined, done: true }