如何在反应中停止递归 setTimeout 函数（clearTimeout 不起作用）？

Question

Thanks for taking a look at this. I am making an api call with recursion to check on a task status update. I had implemented this function last week, and it was working?? Not sure why it doesn't anymore. The conditional that doesn't work is if the status is a FAILURE, it doesn't clearout the timeout, but it does enter the conditional.... Timeout is declared outside the function in the correct context.

export async function exponentialBackoff (checkStatus, task_id, timeout, max, delay, callback) {
    let status = await checkStatus(task_id);
    if (status === "SUCCESS") {
        callback();
    } else {
        if (status === "PENDING") {
            timeout = setTimeout(function() {
                return exponentialBackoff(checkStatus, task_id, timeout, --max, delay * 2, callback);
            }, delay);
        }  else if (status === "FAILURE" || max === 0){
            clearTimeout(timeout);
            return "FAILURE";
        }
    }
}

Answer 1

It looks like a callback hell. I would strongly recommend you to avoid name shadowing and overwriting the arguments.

Also - I believe you don't want to keep the previous timeout alive if a next one was called?

let timeoutInstance;

const clear = (tm) => {
   if (tm) clearTimeout(tm);
};

export async function exponentialBackoff (checkStatus, task_id, max, delay, callback) {
    let status = await checkStatus(task_id);
    if (status === "SUCCESS") {
        callback();
    } else {
        if (status === "PENDING") {
            clear(timeoutInstance);

            timeoutInstance = setTimeout(function() {
                return exponentialBackoff(checkStatus, task_id, --max, delay * 2, callback);
            }, delay);
        }  else if (status === "FAILURE" || max === 0){
            clear(timeoutInstance);

            return "FAILURE";
        }
    }
}