如何在Node.js中创建带有延迟的While循环

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.

Answer 1

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

Answer 2

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