Calling a function multiple times in a while loop

Question

I am trying to get data from a function call and I am keeping it in a while loop so the function will be called again and again if data is not received. What I meant with the data is the data1,data2 and data3 arrays that I have returned from the getData function should be populated and not have a null value. But I am not able to find the solution.

Here is my code :

router.get('/someurl' , async(req,res) => {
let data = [];
while(data.length == 0)
{
  data = await functionCall()
  console.log(data)
   }
})

And here is the format of my functionCall code :

const unirest = require("unirest");
const cheerio = require('cheerio')





const getData = async() => {
   const data1 = [] , data2 = [] , data3 = [] ;
   try {
   const response = await unirest
   .get('url')
   .headers({'Accept': 'application/json', 'Content-Type': 'application/json'})
   .proxy("proxy")
   const $ = cheerio.load(response.body)
   $('hided').each((i,el) =>
   {
         data1[i] = $(el)
         .find('hided')
         .text()
         data2[i] = $(el)
         .find('hided')
   })
   $('hided').each((i,el) =>
   {
         data3[i] = $(el)
         .find('hided')
         .text()
   })
    if(data1.length && data2.length && data3.length))
    {
      return [data1 , data2 , data3]
    }
   }
      catch(error)
      {
         console.log("Error" , error);
      }
      return [];
      }
 
 
module.exports =  getData

This looks like it should work like you expect. Is there any chance that `functionCall()` is returning something on the first call? — outlaw, Mar 25 '22 at 21:22
remove `await`. Also you can remove `if(data.length > 0)`, because your `while` statement do exactly the same by checking `data.length` each iteration. — tarkh, Mar 25 '22 at 21:22
@outlaw, the function can return an null response or an response full of data . — Darshan, Mar 25 '22 at 21:30
@Anonymous2 Well a `null` response won't have a `.length`, so it'll throw an exception. Make it return an empty array instead. — Bergi, Mar 25 '22 at 22:45

score 0 · Answer 1 · answered Mar 25 '22 at 21:24

0

Firstly remove the if statement, as it is literally what the while loop is doing. then remove await, as this is not in an async function, and it will make an error.

answered Mar 25 '22 at 21:24

Cheng Adrian

177
10

Updated the code , I removed the if but still not working – Darshan Mar 25 '22 at 21:31

score 0 · Answer 2 · answered Mar 25 '22 at 21:26

0

Try something like this.

const fetchData = async ()=>{
data = await functionCall()
if(data.length==0){
fetchData()
}else{
return}
}

answered Mar 25 '22 at 21:26

Shivansh Verma

138
6

I want that data1, data2 and data3 inside the data array to be populated. But can't able to find the solution . – Darshan Mar 26 '22 at 12:35

score 0 · Answer 3 · answered Mar 25 '22 at 22:04

Assuming that fetchData is an API call there's no reason to initially define data. You can just log the results of calling that API until the results are an empty array.

const data = [1, 2, 3, 4];

// A simple API that returns a reduced array
// on every call
function mockApi() {
  return new Promise(res => {
    setTimeout(() => {
      res([...data]);
      data.shift();
    }, 1000);
  });
}

// Call the API, and if the the response
// has zero length log "No data" otherwise
// log the data, and call the function again.
async function fetchData() {
  const data = await mockApi();
  if (!data.length) {
    console.log('No data');
  } else {
    console.log(data);
    fetchData();
  }
}

fetchData();

I want that data1, data2 and data3 inside the data array to be populated. But can't able to find the solution . — Darshan, Mar 26 '22 at 12:35

Calling a function multiple times in a while loop

3 Answers3