javascript - The function contains a fetch request. How to return the result of the fetch request through the function?

Question

I will simply write down my thoughts below

function demo(){

let data=[];
fetch(xxx).then((res)=>{
    data.push(res);
})
return data;

}

Since it is an asynchronous request, the returned data is still an empty array, not an array containing the requested data. So is there any way to get the data and then return it?

Answer 1

It is impossible to return the value asynchronously

Values ​​can only be processed in callback functions

Answer 2

function demo(){
    let data=[];
    return fetch(xxx).then((res)=>{
        data.push(res);
    })
}
demo().then(data=>console.log(data))

Answer 3

Use async/await method

async function demo(){
    let data=[];
    await fetch(xxx).then((res)=>{
        data.push(res);
    })
    return data;
}

Then execute the function

Answer 4

Use await, pay attention to the need to build

async function demo(){
    const response = await fetch(url, options);
    // todo: 异常处理
    
    const data = await response.json();
    return data;
}

Refer to es6 await