如何获取js异步请求返回值

Love The Way You Lie 2022-05-31 12:55 387阅读 0赞

使用定时函数模拟异步请求

*  回调函数
    
        function doSomething(callback){
            setTimeout(function(){
                console.log('执行结束');
                let result = 4;
                callback(result);
            },100);
        }
        
        function callback(result){
            console.log('接收到结果为：'+result);
        }
        
        doSomething(callback);
        
        //doSomething((result)=>{console.log('接收到结果为：'+result)});
 *  使用es6提供的Promise函数
    
        function doSomething(){
        
            return new Promise(function(resolve){
                setTimeout(function(){
                    console.log('执行结束');
                    let result = 6;
                    resolve(result);
                },100);
            });
        
        }
        
        doSomething().then(result=>{
            console.log('接收到结果为：'+result);
        });
 *  Generator函数
    
        function doSomething(){
            setTimeout(function(){
                let result = 6;
                it.next(result);
            },100);
        }
        
        function *gener(){
            var result = yield doSomething();
            console.log(result);
        }
        
        let it = gener();
        it.next();
 *  使用es7新特性async
    
        function doSomething(){
            return new Promise(resolve=>{
                setTimeout(function(){
                    let result = 6;
                    resolve(result);
                },100);             
            });
        
        }
        
        async function action(){
            let result = await doSomething();
            console.log(result);
        }
        action();