我一直在尝试创建一个这样的api，其中我尝试了不同的方法，比如使用map/filter/reduce这样的数组方法，在执行api调用之前，我会得到挂起的承诺或返回的结果。 所以我的怀疑是-->；
null
async function getNumDraws(year) {
const goals = [...Array(11).keys()];
let result = 0;
console.log(`before loop ${new Date()}`);
for(let goal of goals){
console.log(`in loop before await ${new Date()}`);
await require('https').get(`https://jsonmock.hackerrank.com/api/football_matches?year=${year}&team1goals=${goal}&team2goals=${goal}`,res=>{
let data="";
res.on('data', (chunk) => {
data += chunk;
});
// The whole res has been received. Print out the result.
res.on('end', () => {
data=JSON.parse(data);
console.log(result,data.total)
result= result + data.total;
});
})
console.log(`in loop after await ${new Date()}`);
}
console.log(`after loop ${new Date()}`);
return result;
console.log(getNumDraws(2011));
}null
https.get是一个回调函数，因此await无法工作。 你应该首先承诺它，就像他们在另一个问题中所做的那样；
const https = require("https"); // only require this once
const getJSONAsync = url => new Promise((resolve, reject) => { // define a function getJSONAsync which returns a Promise that wraps the https.get call, getJSONAsync is awaitable
let req = https.get(url, res => { // make the https.get request
if(res.statusCode < 200 || res.statusCode >= 300) { // if the status code is an error one
return reject(new Error('statusCode=' + res.statusCode)); // reject and skip the rest
}
let body = []; // otherwise accumulate..
res.on('data', chunk => body.push(chunk)); // ..the data
res.on('end', () => { // on end
try {
body = JSON.parse(Buffer.concat(body).toString()); // try to JSON.parse the data
} catch(e) {
reject(e); // reject if an error occurs
}
resolve(body); // resolve the parsed json object otherwise
});
});
req.on("error", error => reject(error)); // reject if the request fails too (if something went wrong before the request is sent for example)
});
async function getNumDraws(year) {
let result = 0;
for(let goal = 0; goal < 11; goal++) {
let data = await getJSONAsync(`https://jsonmock.hackerrank.com/api/football_matches?year=${year}&team1goals=${goal}&team2goals=${goal}`);
result += data.total;
}
return result;
}
注意:GetJsonAsync并不特定于GetNumDraus，如果需要，您可以在其他地方使用它，并且由于它返回了一个Promise，您可以像GetNumDrausdoes那样Await它，或者像这样将它与Then/Catch块一起使用:
getJSONAsync("url")
.then(data => {
// data is the parsed json returned by the request
})
.catch(error => {
// the error message if something fails
})
