Accessing variables in an asynchronous function without jQuery

Asked May 09 '17 at 13:12

Active May 09 '17 at 13:48

Viewed 18 times

How can I access variables in an asynchronous function declared previously? I suppose I have to pass them as parameters but how do I do this?

The problem is, by the time http is loaded, i and other data has changed since the function call is asynchronous.

var myDataInitializedBefore = ...;

for (var i = 0; i < myDataInitializedBefore.length; ++i)
{
    var http = new XMLHttpRequest();
    http.open("GET", myUrl, true);
    http.responseType = "blob";
    http.onload = function(e) 
    {
        if (this.status == 200)
        {
            --> do something with myDataInitializedBefore[i] and some other variables
        }
    }
}

edited May 09 '17 at 13:48

asked May 09 '17 at 13:12

Sceptical Jule

That will work, as you have it :) – bluehipy May 09 '17 at 13:14
@bluehipy nope it wont... – Jonas Wilms May 09 '17 at 13:23
the local var will be accessible as you describe but it will not work as you expect as i will have the value from the end of the loop. – bluehipy May 09 '17 at 13:27
Your suggested solution shows only how to call a simple function within a closure. Using closures with `XMLHttpRequests` WITHOUT jQuery is not trivial. – Sceptical Jule May 09 '17 at 13:46

Accessing variables in an asynchronous function without jQuery

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