Promise not returning value of request

Question

I have this promise:

function getAPI(token)
{
return new Promise((resolve, reject) => {
    console.log(\"Request API\");
    GM_xmlhttpRequest({
        meth         


        

Answer 1

You're creating multiple promises, because each call to getAPI creates and returns a new promise.

getAPI shouldn't call itself (or if it does, it should pass the new promise into resolve); instead, just retry the part within it you need to retry, something along these lines:

function getAPI(token) {
    return new Promise((resolve, reject) => {
        // Function to do the request
        function doRequest() {
            console.log("Request API");
            GM_xmlhttpRequest({
                method: "GET",
                url: "URL" + token,
                onload: function(response) {
                    console.log(response.responseText);
                    if (response.responseText == "NOT_ANSWER" || response.responseText.indexOf("ERRO") > -1) {
                        // Not what we wanted, retry
                        console.log(response.responseText + " - Calling Myself in 5 Seconds");
                        setTimeout(doRequest, 5000);
                    }
                    else {
                        console.log('Call API - Giving Result');
                        resolve(response.responseText.split("_")[1]);
                    }
                }
            });
        }
        doRequest();
    });
}

---

Side note: Your code using getAPI is checking for promise rejection, but nothing in getAPI ever rejects the promise.

Answer 2

I call it inside of itself when the answer is not what i want,

and then you don't call resolve of the promise which you had returned from the top getAPI call, so the promise never settles and your then callback never gets any result.

You should promisify your asynchronous functions GM_xmlhttpRequest and setTimeout on the lowest level, and then only chain your promises. By returning the result of the recursive call from a then callback, the resulting promise will resolve with the same result:

function xhrAsync(url) {
    return new Promise((resolve, reject) => {
        GM_xmlhttpRequest({
            method: "GET",
            url: url,
            onload: resolve
        });
    });
}
function delayAsync(time) {
    return new Promise(resolve => {
        setTimeout(resolve, time);
    });
}
function getAPI(token) {
    console.log("Request API");
    return xhrAsync("URL"+token).then(response => {
//  ^^^^^^                       ^^^^
        console.log(response.responseText);
        if (response.responseText == "NOT_ANSWER" || response.responseText.includes("ERRO")) {
            console.log(response.responseText + " - Calling Myself in 5 Seconds");
            return delayAsync(5000).then(() => {
//          ^^^^^^                  ^^^^
                return getAPI(token);
//              ^^^^^^
            });
        } else {
            console.log('Call API - Giving Result');
            return response.responseText.split("_")[1];
        }
    });
}