Javascript for loop pass in counting variable

Question

   for (var i=0 ; i<10 ; i++){

      var myFunction = function(something){
         console.log(i);
      }

      $.ajax({

        url: "something.json",
        dataType: "json",
        success: function( response ) {

               myFunction(response.something);

        }
      });               

    }

How do I access latest i in myFunction every time when loop through the for loop. It seems that the latest i in myFunction is not accessible, so it does not log from i = 0 to 9.

are you creating a function and doing ajax call inside the loop? — David Chase, Mar 19 '14 at 17:56
I want to do 9 times of ajax call, and for each ajax call, I want to invoke the "myFunction", and log the i. — Terry Chen, Mar 19 '14 at 17:58

score 1 · Answer 1 · answered Mar 19 '14 at 18:41

This probably is not the most efficient solution. But it does work. You can set object variables to the request and access them by using .call on myFunction

for (var i=0 ; i<10 ; i++){

  var myFunction = function(something){
     console.log(this.localData.i);
  }

  $.ajax({
      url: "/echo/json/",
      dataType: "json",
      //Set the i variable to this request
      localData: {
          i: i
      },
      success: function( response ) {
        //call myFunction with this as the context, and you'll be able to access localData by using this.localData.i
        myFunction.call(this, response.something)
      }
  });               

}

Heres a fiddle: http://jsfiddle.net/XxRAv/1/

score 0 · Answer 2 · answered Mar 19 '14 at 17:59

      function myFunction(i,something){
         console.log(i);
         console.log(something);
      }

    for (var i=0 ; i<10 ; i++){
      $.ajax({

        url: "something.json",
        dataType: "json",
        success: function( response ) {

               myFunction(response.something);

        }
      });               

    }

score 0 · Answer 3 · answered Mar 19 '14 at 17:59

0

You're seeing the effects of late binding. One solution is to create a wrapper function and call it which will return the correct function:

  var myFunction = function(i){ 
     return function(something){ console.log(i); };
  }(i);

answered Mar 19 '14 at 17:59

mgilson

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Javascript for loop pass in counting variable

3 Answers3