// simple calculation with promise-chain // then 会包装成一个新的Promise对象, 并把return作为参数引入

data_transfer_promise.js

let initNum = 10;
Promise.resolve(initNum).then(function add(num) { //  fulfilled function
	num += 10;
	console.log('add 10 to =>' + num);
	return num;
}, function addRej(num) { //  onReject
  console.log('Reject add operation.');
}).then(function devide(num) {
	num /= 4;
	console.log('devided by 2 => ' + num);
}).catch(function(error) {
	console.error(erro);
});