how to run a function inside function asynchronously?

Question

I am making a payment gateway for my web site and I have problem with my debugger. Even I have used async await even then some particular lines are executed asynchronously but when another function comes it runs sync. For better understanding have a look on the actual code mentioned below

This is my app.js file

app.post('/pay', async function(req,res){

let response = await orderApi.pay(req.body)  // First debugger goes here (1)
res.json(response)  // (need this line to be executed when pay function is completed) (4)
console.log(response)

And this is my order API file

exports.pay = async function (body) {
  var headers = { //then here debugger comes (2)
    'X-Api-Key': 'test_d5f178f6f910a5ec48a429d540d',
    'X-Auth-Token': 'test_f3f32cda3a7aafc2a188579530f'
  }
 

  var payload = {
    purpose: body.purpose,
    amount: body.amount,
    phone: body.phone,
    buyer_name: body.buyer_name, 
   
  }
  request.post('https://test.instamojo.com/api/1.1/payment-requests/', { form: payload, headers: headers }, function (error, response) { // (3) !!!
       var parsed = JSON.parse(response.body); // then it does not goes here then it goes back in app.js file (5)
      var redirectu = parsed.payment_request.longurl (6)
      return redirectu
   
  })
}

I am not able to understand what problem it please help me to figure it out // remember the points like (1),(2).. they are the numbers where my debugger goes

Answer 1

You probably want to return what's coming back from request.post which means that we should modify the code to something like the following:

const response = await request.post('https://test.instamojo.com/api/1.1/payment-requests/', { form: payload, headers: headers });
const parsed = JSON.parse(response.body);
const redirectu = parsed.payment_request.longurl(6);
return redirect;

Explanation

The return inside the callback of request.post is returning after the function already finished executing and since there's no explicit return in the outer function, it just calls request.post and (implicitly) returns undefined without waiting for the request.post to finish executing.