How can I use fetch in while loop

Question

My code is something like this:

var trueOrFalse = true;
while(trueOrFalse){
    fetch(\'some/address\').then(){
        if(someCondition){
            trueOrFals         


        

Answer 1

while(true) creates an infinite loop, which will attempt to call fetch infinitely many times within a single "tick". Since it never finishes issuing new fetch calls, it never gets to the next tick.

This function is very CPU-intensive and will probably lock up the entire page.

---

What's the solution?

What you are probably trying to do is keep fetching until the result satisfies some condition. You can achieve that by checking the condition in the then callback, and re-issuing the fetch if it is false:

var resultFound = false;

var fetchNow = function() {
  fetch('some/address').then(function() {
    if(someCondition) {
      resultFound = true;
    }
    else {
      fetchNow();
    }
  });
}

fetchNow();

This way, instead of

fetch!
fetch!
fetch!
fetch!
...

...the behavior is going to be

fetch!
  wait for response
  check condition
if false, fetch!
  wait for response
  check condition
if true, stop.

...which is probably what you expected.