SOURCE

function runAsync(){
    var p = new Promise(function(resolve, reject){
        //做一些异步操作
        setTimeout(function(){
            console.log('执行完成');
            reject('reject')
        }, 2000);
    });
    return p;            
}
runAsync().then((resolve)=>{
    console.log('resolve')
}).catch((reject)=>{
    console.log('reject')
})