Why doesn't my for each loop run in IE?

There are a few critical points in your code that might fail if conditions are not as you expect. One simple but effective approach is to insert Javascript alert() statements at points through the loop to check the outcome of each condition

There are a few critical points in your code that might fail if conditions are not as you expect. One simple but effective approach is to insert Javascript alert() statements at points through the loop to check the outcome of each condition, e.g.

if (data) {

  alert('The data variable evaluates to true.');

  // Else none of the following executes...

  ...
    
It is not clear where the variable data originates and whether you would always expect it to have a value. Where does the key reference below originate, what does it refer to?

  ...
  for (key in data[i]) {

    alert('Data value ' + i + ' = ' + data[i]);
  }
  ...
    
Does this loop run at all? What values do you get? This simple alert() based technique can give quick insights to where your code may fail. Some browser add-ons and developer consoles allow you to step through Javascript as it executes and inspect values in more detail.