How to create a while loop with delay in nodejs

Question

Let's say I have this pseudo code:

var STATUS = '';
while (STATUS !== "SUCCEEDED") {
    STATUS = getStatus();
    anotherFunc();
    delay(3s);
}

The goal of this code is to keep calling an api to check a status of something, the api returns IN_PROGRESS or SUCCEEDED. So I want the while loop to keep calling getStatus() to get the value of STATUS and break the loop when it is SUCCEEDED. I also want to put a delay between each iteration.

This can't be done easily with Nodejs. So please help me out.

Restructure using a promise and setTimeout()-based retries? — nnnnnn
– nnnnnn, Commented Sep 23, 2017 at 1:21

Kristianmitk · Accepted Answer · 2017-09-23 01:27:54Z

2

you don't even need a while loop for that, simply use setInterval() and within the callback check if your condition is satisfied to clear the created interval.

var STATUS = '',
    idx = setInterval(function() {
        STATUS = getStatus();
        if (STATUS === "SUCCEEDED") { // I guess you wanted a check for STATUS instead of VAR
            return clearInterval(idx);
        }
        anotherFunc();
    }, 3000); // the interval when to call the function again 3000ms = 3sek

answered Sep 23, 2017 at 1:27

Kristianmitk

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2 Comments

Casper Over a year ago

for some reason this code only runs once when I test

Kristianmitk Over a year ago

this would implicate that the getStatus() function returned "SUCCEEDED" after the second time. You can fake getStatus and see when no "SUCCEEDED" is ever returned the setInterval callback will be called consequently

DillGromble · Accepted Answer · 2017-09-23 01:22:45Z

0

You can use setInterval to continually do something on a delay. It accepts a function which you can use to do the api call, but before you do the call you should check if the last call was successful.

Once a call is successful you can clear the interval.

https://nodejs.org/api/timers.html#timers_setinterval_callback_delay_args

answered Sep 23, 2017 at 1:22

DillGromble

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