While loop on Node.js with asynchronous data

Question

I'm using the Request module to make a GET request on Node.js. However the while loop is never broken.

//this function calls the paging function until page.paging.next is undefined
function createLikes(page){
  addLikes(page)
  while (typeof page.paging.next !== "undefined") {
    paging(page,function(resp){
      page = resp
      console.log(page)
    })
  }
}

function paging(page, callback){
  request.get({url: page.paging.next},
  (error, response, body) => {
  if(error) {
    return console.dir(error);
  }
  return callback(JSON.parse(body))
  })
}

How can i fix this considering that console.log inside the callback function logs the expected data?

Edit:

I used the solution given below by CertainPerformance and it worked out up to the point that it needed to exit the loop, then it gave me a unhandled promise rejection error. What's wrong?

Something tells me that paging() should also have a way of communicating back an error. — jfriend00
– jfriend00, Commented Mar 26, 2018 at 3:06

CertainPerformance · Accepted Answer · 2018-03-26 02:23:04Z

4

paging runs asynchronously, but your while loop runs synchronously. Try using await instead, so that the while loop waits for the asynchronous resolution with each iteration:

async function createLikes(page) {
  addLikes(page)
  while (typeof page.paging.next !== "undefined") {
    page = await new Promise((resolve, reject) => {
      paging(page, resolve);
    });
  }
}

answered Mar 26, 2018 at 2:23

CertainPerformance

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1 Comment

Matt Over a year ago

There's also request-promise to avoid the callback shenanigans.

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