Question

Why does this code always return 0?

     var possibleMatches = new Array();
  $.getJSON('getInformation.php', function(data) {
   $.each(data, function(i){
    possibleMatches.push(data[i]);
   })
  });
  alert(possibleMatches.length);

Though I can move or add “alert(possibleMatches.length);” inside the $.each and it will output the correct number of elements.

I’m just curious as to why it the values aren’t going into the array as I expected. I’m sure its a local variable vs. global variable issue, just not sure why.

Basically, what this is trying to do is fill the possibleMatches array with the data results.

thanks!

Answer 1

Asynchronicity. The line alert(possibleMatches.length); executes before the success callback for $.getJSON() executes.

So, to have your alert report accurately, just move it.

var possibleMatches = new Array();
$.getJSON('getInformation.php', function(data) {
  $.each(data, function(i){
    possibleMatches.push(data[i]);
  })

  // To here
  alert(possibleMatches.length);
});
// From here

Remember, the first A in AJAX stands for “Asynchronous”