ES: Promise的基本用法

let myRandom=Math.floor(Math.random() * 10 );

var workIsDone=new Promise(
  (resolve,reject) =>{
    if(myRandom<5){
      resolve("finished......")
    }
    else{
      reject("ongoing......")
    }
  }

)

workIsDone.then(function(value) {
  console.log("ok: "+value)
  }, function(error) {
  console.log("error: "+error);
});