Node.js中的Https请求

Question

I'm using the request library in Node.js to do a https request to get data from another service. This is called asynchronously, right? So my code keeps running before all of the data is there, correct?

My problem is that the data is needed right afterwards to calculate some things. My code throws an error during that calculation because the data from the service is undefined... Could it be possible that the data is just not there yet? And if so, what do you do against that?

Here is a copy of the request:

const request = require('request');

request(someUrl, {"Accept": "application/json"}, (err, res, body) => {
    if (err)
        handleError(err);
    body = JSON.parse(body);
    return body;
});

Answer 1

This kind of situation is pretty common in react/angular/vue kinda web apps, sometimes you need the data right away. But it is not available then, after a Rest call or something it becomes available.

So, the simplest solution?
Just add a check , for example:

const calculate = (someVal)=>{
    if(!someVal) return ;
    //otherwise do the calculation
}

There are plenty of other ways, by mostly making the calculation async. For your function, you can do this

const promOp = function(){
    return new Promise((resolve, reject) => {
        request(someUrl, {"Accept": "application/json"}, (err, res, body) => {
            if (err) reject(err);
            body = JSON.parse(body);
            resolve(body);
        });
    }
}
//then
promOp()
.then((body)=>{
    //calculate here
})

//or can use the `Async/Await` syntax instead of then
const op = async () => {
    const body = await promOp;
    //calculate here
}