How to access index variable in a jquery getJson call ($.getJson) during a loop?

Question

I have the following code, which has been simplified for this question. Basically i have a loop, that, on each iteration, calls the jquery getJSON function, calling out to a API end point to grab some weather data. The problem is that i need to access the index from the loop, when the getJSON request was fired, and am having some troubles with it. I need to know what index the request was for, so i can match it with some data from a database.

The code:

function buildCities()
{    
    for (var i = 0; i < 7; i++) 
    {
        var jqxhr = $.getJSON("http://api.openweathermap.org/data/2.5/weather?q=usa,phoenix&units=metric", function(response) 
       {
           alert(i); //this will always be 7 - this is the issue.  i desire it to be 0,1,2,3, etc.... 
       });
    }
}

Here is a JSFiddle that shows the issue, and that you can work on if need be ;) - http://jsfiddle.net/5tr34k/0xshvrzp/

The request: How can i inject or otherwise access this index (i) inside of the callback function for the request ? Thanks for any help.

iCollect.it Ltd · Accepted Answer · 2015-03-13 15:11:49Z

4

Add a scoping function (an IIFE) that creates a new scope for your variable:

function buildCities()
{    
    for (var i = 0; i < 7; i++) 
    {
        (function(index){
            var jqxhr = $.getJSON("http://api.openweathermap.org/data/2.5/weather?q=usa,phoenix&units=metric", function(response) 
           {
                alert(index); 
           });
        })(i);
    }
}

answered Mar 13, 2015 at 15:11

iCollect.it Ltd

93.9k26 gold badges189 silver badges210 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

ayla Over a year ago

wickedy! this works pretty good. now i just need the stupid API to respond better to quick calls!

iCollect.it Ltd Over a year ago

@jordan.peoples: Yes "Types" are available in "Stereo", but not recommended :)

Abraham Adam · Accepted Answer · 2015-03-13 15:15:05Z

0

Also if you have access to ES6 changing i to val instead of var will also work.

Main issue is you are dealing with function scoping so you keep reusing the same variable vs val which is {} scoped, or TrueBlueAussie answer which creates a new scope for you.

answered Mar 13, 2015 at 15:15

Abraham Adam

6331 gold badge6 silver badges16 bronze badges

3 Comments

iCollect.it Ltd Over a year ago

Are your seriously suggesting an upcoming standard as a solution for a current real-world problem? :)

Abraham Adam Over a year ago

Ecmascript 6 is the newest version of javascript standard , @TrueBlueAussie you already had a good answer while I was writing mine so was just thinking of another way to add value instead of rewriting yours with different flavor lol.

iCollect.it Ltd Over a year ago

Come back in a couple of years and your answer will, one day, be the preferred solution :)

Collectives™ on Stack Overflow

How to access index variable in a jquery getJson call ($.getJson) during a loop?

2 Answers 2

2 Comments

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related