javascript - 如何发出异步请求以使用javascript同步请求(how to make async request to sync request using javascript)

Question

 function abc() {
    console.log(0)
    console.log(1)
 setTimeout(() => {
        console.log(2)
    },0)
    console.log(3)
}
abc()

I know this is async request how can i make it to sync.(我知道这是一个异步请求，我如何使其同步。)

Can anyone help me on this please output should be 0,1,2,3(谁能帮我这个，请输出为0、1、2、3)   ask by Shivam translate from so

Answer 1

In javascript there are three ways to handle asynchronous calls, callbacks (deprecated) , Promises (only when you must) and async/await (recommanded) .(在javascript中，有三种方法可以处理异步调用： callbacks （不建议使用） ， Promises （仅在必须时）和async/await （建议） 。)

Using async/await(使用async/await)

 function asyncFunction() { return new Promise((resolve) => { setTimeout(() => { console.log(2); resolve(); }, 0); }); } async function abc() { console.log(0); console.log(1); await asyncFunction(); console.log(3); } abc(); 

Using Promises(使用Promises)

 function asyncFunction() { return new Promise((resolve) => { setTimeout(() => { console.log(2); resolve(); }, 0); }); } function abc() { return new Promise((resolve) => { console.log(0); console.log(1); asyncFunction() .then(() => { console.log(3); resolve(); }); }); } abc(); 

There are tons of tutorials online explaining what theses are and how to use properly.(在线上有大量教程，解释了这些内容以及如何正确使用。)