Promise 捕获程序中的失败

代码

var A = new Promise(function (resolve, reject) {
  console.log('do sth.');
  setTimeout(() => {
    console.log('~~~~~');
    resolve('ok');
    // reject('error ******');
    console.log('+++++');
  }, 3000); // 延时3秒执行一次结束
});

//    var B = A.then()  //穿透
var B = A.then(
    //处理失败上一个Promise的成功，并返回自己生成的Promise的返回值（默认返回undefined resolve(2222)）利用Promise.reject(reason)传给下个promise异常
    value => {console.log(111, value);return Promise.reject(2222)},
    reason => {console.log(222, reason);return 'A.then.error';});   //处理失败上一个Promise的失败，并返回自己生成的Promise的返回值

// setInterval(() => {
//   console.log(A);
//   console.log(B);
//   console.log('~~~~~~~~~~~~~~~~~~~~');
// }, 1000);

// 捕获程序中的失败
let p3 = B.catch(
    reason => console.log('main: ', reason)
)

console.log('===================');

效果

root@ubuntu:~/workspace/es6/babel# node dist/index.js 
Debugger attached.
do sth.
===================
~~~~~
+++++
111 ok
main:  2222
Waiting for the debugger to disconnect...