javascript es6 Promise 异步同步的写法(史上最简单的教程了)详解编程语言

var p = new Promise(function(resolve, reject){ 
//做一些异步操作 
setTimeout(function(){ 
console.log('2秒后执行完成Promise'); 
}, 2000); 
}); 
var p = new Promise(function(resolve, reject){ 
//做一些异步操作 
setTimeout(function(){ 
console.log('1秒后执行完成Promise'); 
}, 1000); 
});

var p1 = new Promise(function(resolve, reject){ 
        //做一些异步操作 
        setTimeout(function(){ 
            console.log('执行完成Promise'); 
            resolve('要返回的数据可以任何数据例如接口返回数据'); 
        }, 2000); 
    }); 
p1.then(function(data){console.log(data)});

function doubleAfter2seconds(num) { 
    return new Promise((resolve, reject) => { 
        setTimeout(() => { 
            resolve('2秒后触发'); 
        }, 2000); 
    } ) 
} 
function doubleAfter1seconds(num) { 
    return new Promise((resolve, reject) => { 
        setTimeout(() => { 
            resolve('1秒后触发') 
        }, 1000); 
    } ) 
} 
 var result = await doubleAfter2seconds(30); 
 console.log(result); 
 var result = await doubleAfter1seconds(30); 
    console.log(result);