菜鸟教程 promise
https://www.runoob.com/js/js-promise.html
https://www.runoob.com/w3cnote/es6-promise.html
JavaScript 异步编程
https://www.runoob.com/js/js-async.html
https://www.runoob.com/js/js-promise.html
https://www.runoob.com/w3cnote/es6-promise.html
https://www.runoob.com/js/js-async.html