Cant change a '(not completely) global variable' from a function javascript

Asked Feb 22 '17 at 20:26

Active Feb 22 '17 at 20:26

Viewed 26 times

I would like teacherID to be returned from this function so I defined the variable outside the function the actual value is created but it doesn't seem to be working any help? (P.S. Was not sure what this sort of variable is called )

function getTeacherID(courseID,block,roomID){
    //Get the rooms for the subjects the student does
    var teacherID;
    function doXHRPromise() {
        return new Promise(function(resolve, reject) {
            var xmlhttp = new XMLHttpRequest();
            xmlhttp.onreadystatechange = function() {
                if (this.readyState == 4 && this.status == 200) {
                    resolve(this.responseText);
                }
            }
            var everythingArray = [courseID,block,roomID];
            xmlhttp.open("GET", "getTeacherIDTimetable.php?q=" + JSON.stringify(everythingArray), true);
            xmlhttp.send(); 
        });
    }
    doXHRPromise().then(function(responseText) {
        teacherID = responseText;
    });
    return teacherID;
}

asked Feb 22 '17 at 20:26

Dilly

Your then runs after you've returned the value. Its still async. Just return the promise and attach a then in your calling code. – ste2425 Feb 22 '17 at 20:28
Welcome to the wonderful world of **async**! You can't do that. – SLaks Feb 22 '17 at 20:28
callback maybe? – Luminous_Dev Feb 22 '17 at 20:29
You could wait for resolve the async method by calling `Promise.resolve(object)` :) But this is bad practice at all – marpme Feb 22 '17 at 20:29
1

@Kyon: That won't do anything. – SLaks Feb 22 '17 at 20:33
@SLaks I know it's the same like using `.then()` – marpme Feb 22 '17 at 20:34
I have looked at the question that this is meant to be a duplicate of and it does not help at all – Dilly Feb 22 '17 at 20:53
You need to return and use the promise. http://blog.slaks.net/2015-01-05/introducing-promises/ – SLaks Feb 22 '17 at 20:56
@SLaks How do you return the promise? – Dilly Feb 22 '17 at 21:05

Cant change a '(not completely) global variable' from a function javascript

0 Answers0