Get response from axios with await/async

问题:

I'm trying to get JSON object from axios

'use strict'

async function getData() {
    try {
        var ip = location.host;
        await axios({
            url: http() + ip + '/getData',
            method: 'POST',
            timeout: 8000,
            headers: {
                'Content-Type': 'application/json',
            }
        }).then(function (res) {
            console.dir(res); // we are good here, the res has the JSON data
            return res; 
        }).catch(function (err) {
            console.error(err);
        })
    }
    catch (err) {
        console.error(err);
    }
}

Now I need to fetch the res

let dataObj;
getData().then(function (result) {
    console.dir(result); // Ooops, the result is undefined
    dataObj = result;
});

The code is blocking and waits for the result, but I'm getting undefined instead of object

回答1:

This seems to be one of those cases where async/await doesn't buy you much. You still need to return a result from the async function, which will return a promise to the caller. You can do that with something like:

async function getData() {
    try {
       let res = await axios({
            url: 'https://jsonplaceholder.typicode.com/posts/1',
            method: 'get',
            timeout: 8000,
            headers: {
                'Content-Type': 'application/json',
            }
        })
        if(res.status == 200){
            // test for status you want, etc
            console.log(res.status)
        }    
        // Don't forget to return something   
        return res.data
    }
    catch (err) {
        console.error(err);
    }
}

getData()
.then(res => console.log(res))

<script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.18.0/axios.js"></script>

But in this example, since you don't need to do much in the actual function with the result, you're probably better off just returning axios's promise:

function getDataPromise() {
    return axios({
            url: 'https://jsonplaceholder.typicode.com/posts/1',
            method: 'get',
            timeout: 8000,
            headers: {
                'Content-Type': 'application/json',
            }
        })
       .then(res => res.data)
       .catch (err => console.error(err))
    }


getDataPromise()
.then(res => console.log(res))

<script src="https://cdnjs.cloudflare.com/ajax/libs/axios/0.18.0/axios.js"></script>

回答2:

I think you didn't understand correctly about promise and async/await on javascript. Please try like this:

function getData(url, method) {
    var ip = location.host;
    return axios({
        url: url,
        method: method,
        timeout: 8000,
        headers: {
            'Content-Type': 'application/json',
        }
    })
}

let dataObj;
let url = http() + ip + '/getData', method = 'post';
getData(url, method)
.then(function (result) {
    console.dir(result);
    dataObj = result;
})
.catch(function(error){
    console.log(error);
});

async/await:

function getData(url, method) {
    var ip = location.host;
    return axios({
        url: url,
        method: method,
        timeout: 8000,
        headers: {
            'Content-Type': 'application/json',
        }
    })
}
(async function(){
    let dataObj;
    let url = http() + ip + '/getData', method = 'post';
    try{
        const result = await getData(url, method);
        dataObj = result;
    } catch (error) {
        console.log(error);
    }
})();