React native 之 Promise

关键词：Promise Promise.all  

 

Promise是什么？=> https://www.runoob.com/w3cnote/es6-promise.html 

 

Promise.all 和 Promise.race => https://www.jianshu.com/p/7e60fc1be1b2  和 https://www.cnblogs.com/lcspring/p/11169295.html