我对这段代码有问题:
var request = require('request-promise');
class Test{
constructor(){
}
async Start(){
var response = await this.getResponse();
await console.log(response);
}
async getResponse(){
var options = {
uri: "https://www.google.com"
}
var response = await request(options);
setTimeout(function(){
return response;
},1000);
}
}
module.exports = Test;
当我运行 Start() 时,控制台记录“未定义”,但这是为什么呢?我知道我在返回时设置了 1 秒延迟,但是代码不应该等到返回吗?因为等待?
P.S:延迟是为了模拟正在处理的响应数据。
您不能将“return”放在另一个函数内部并期望它返回到外部函数。 (最大的问题)
async getResponse(){
setTimeout(function(){
return "Test";
},1000);
return undefined; // line is basically what is here when you don't return anything
}
await getReponse(); // returns undefined, NOT "Test".
您可以这样编写代码:
const delay = time => new Promise(res=>setTimeout(res,time));
class Test{
constructor(){
}
async Start(){
var response = await this.getResponse();
console.log(response); // await not needed here.
}
async getResponse(){
var options = {
uri: "https://www.google.com"
}
var response = await request(options);
await delay(1000); // since we're using async functions, we can "await" a promise
return response;
// previous code would return "undefined" when after it called setTimeout
}
}
module.exports = Test;
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