Promise，我们来实战

并发执行多个异步方法，统一返回结果，结果按照参数的顺序返回。

const getRandom = () => +(Math.random()*1000).toFixed(0); const asyncTask = taskID => new Promise(resolve => { let timeout = getRandom(); console.log(`taskID=${taskID} start.`); setTimeout(function() { console.log(`taskID=${taskID} finished in time=${timeout}.`); resolve(taskID) }, timeout); }); Promise.all([asyncTask(1),asyncTask(2),asyncTask(3)]) .then(resultList => { console.log('results:',resultList); });