Question

I have a list of link , when I click on it , I want to count the elements that contain in my list. This is what I coded:

$('a#' + dataOption.ID).click(function () {
  $.getJSON("ProductListing/Index", data, function (product) {
     $.each(product.ja, function (index, value) {
        num_obj = product.ja.length;
     });
  });
});
alert(num_obj);

The alert is Undefined.

The JSON result is :

{"ja":
[
   {"Name":"ABC1","PictureName1":"my image name1","ID":1},   
   {"Name":"ABC2","PictureName2":"my image name2","ID":2}
]}

Could anyone tell me, how can I count that JSON in my click event. Thans so much.

Answer 1

The code you’ve posted creates a click handler and then immediately does an alert(num_obj) – given that num_obj isn’t declared anywhere and the click event itself hasn’t happened yet, num_obj is supposed to be undefined at that point.

Try moving the alert into the callback of the $.getJSON() function, to just after the first point where num_obj actually has a value assigned:

$('a#' + dataOption.ID).click(function () {
  $.getJSON("ProductListing/Index", data, function (product) {
     var num_obj = product.ja.length;
     alert(num_obj);
  });
});

Note that I’ve removed the $.each() since it doesn’t make sense to iterate over the product.ja array and test product.ja.length for each element (the fact that you didn’t use this or index or value inside the $.each() was also a clue that you didn’t need the each).