Promis.then()

1     function cook() {
 2       console.log('开始做饭。');
 3       var p = new Promise(function (resolve, reject) {
 4         setTimeout(function () {
 5           console.log('做饭完毕！');
 6           resolve('鸡蛋炒饭');
 7         }, 1000);
 8       });
 9       return p;
10     }
11
12     function eat(data) {
13       console.log('开始吃饭：' + data);
14       var p = new Promise(function (resolve, reject) {
15         setTimeout(function () {
16           console.log('吃饭完毕!');
17           resolve('一块碗和一双筷子');
18         }, 2000);
19       });
20       return p;
21     }
22     function wash(data) {
23       console.log('开始洗碗：' + data);
24       var p = new Promise(function (resolve, reject) {
25         setTimeout(function () {
26           console.log('洗碗完毕!');
27           resolve('干净的碗筷');
28         }, 2000);
29       });
30       return p;
31     }
32
33     cook()
34       .then(eat)
35       .then(wash)
36       .then(function (data) {
37         console.log(data);
38       });

输出：

备注：resolve只能传入一个参数，传入的其它参数，读取到的值为"undefined"。