$.ajax in a for loop pulling from a php file

Question

I have a key_gen.php file that contains a function to generate a random key. When executed, the php file gives back one key (tested and it works).

In my javascript file I have a click event on a button (that works), something like this:

$('#kg_btn').click(function(){});

Then, inside my click event I have a functions:

         var get_key = function(){
            for(var i = 0; i < kg_quantity; i++) {
                $.ajax ({
                    url: "../keygen/gen_rkey.php",
                    type: "GET",
                    datatype: "json",
                    success: function(data) {
                        var j_obj = JSON.parse(data);
                        //alert("Success!");
                        prs = j_obj.test;
                        console.log(prs);
                        //add_key();

                    },
                    error: function(error) {
                        alert("Error! Can't send the data");
                    }
                }); //ajax call ends 

            }
        }

When I run this function once (by setting up the "Kg_quantity" variable to 1), every time I click my button I get a correct behavior. The result is a different key on the console.log per click.

If I set up the "kg_quantity" to any other number than 1 (for example: 3,9,10), I do get the console.log messages back, but the number generated is the same.

I was hoping that by inserting the ajax object into a for-loop would execute the ajax call several times. I tried to put the ajax call within a prototype function, as well, but I get the same result.

Edit: I tried adding a closure (as Ross suggested), but I get the exact same result.

Thanks.

It could be a caching problem, try passing a parameter to the url that's different every time and see if it helps. — Rafael
– Rafael, Commented Aug 9, 2013 at 17:22
Do you realy need to use JSON.parse(data)? Doesn't jquery read the json automaitcally? Why don't you send the number of keys you need in a single request, then insert inside an array and send them back? After this you can loop through data — Razorphyn
– Razorphyn, Commented Aug 9, 2013 at 17:23
Dheed7, thanks for your answer.The key_gen process is triggered by a js process. I do not know how many keys will be generated (before-hand). On the same page there is an input field and a button. Based on the number the user inserts into the input-field. Ideally, I would have a function that would retrieve as many random-keys as needed through a loop. — Nactus
– Nactus, Commented Aug 9, 2013 at 17:33

SeanCannon · Accepted Answer · 2013-08-09 18:06:46Z

3

AJAX is asynchronous. Your loop will finish before the first AJAX response most likely.

I would restructure that so the success response from the AJAX call will trigger the next iteration. Or if you're lazy you can just set async:false:

$.ajax ({
    url: "../keygen/gen_rkey.php",
    type: "GET",
    async: false,
    ....

Or even better, put the strain on the server and reduce the back-and-forth so you get all your keys in one response:

url: "../keygen/gen_rkey.php?qty=" + kg_quantity,

UPDATE: Async design method:

function getKeys(max,cur) {
    cur = cur || 1;
    if (cur == max) {
        return;
    }
    $.ajax({
        ....
        success(function(data) {
             // do stuff....

            // recursive iteration
            getKeys(max,cur + 1);
        }
    });
}
getKeys(5);

edited Aug 9, 2013 at 18:06

answered Aug 9, 2013 at 17:18

SeanCannon

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1 Comment

Nactus Over a year ago

AlienWebguy, thanks for your answer. I'd love to be able to keep it asynchronous. Can you give me a very simple, fast example on how to have the success affect the loop?

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