function expression/event detection not working in ie<=9 or Safari

Question

I've been searching for an answer to this for about a day now, I have a function that just won't work in IE9 or below or Safari. I think it's because it's triggered by a keyboard event. It also passes the event to the function so onkeyup the function can check the value and act accordingly.

I was wonder if anyone could enlighten me as to what the problem is, the function is as follows:

window.onkeyup = function(e) { //This doesn't seem to work in the above browsers

   var key = e.keyCode ? e.keyCode : e.which; //But neither does this

   if (key == 83 && array.length>=0) {

        // Log answer as 'S'

   }else if (key == 68 && array.length>=0) {

        //Log answer as 'D'

   }

}   

Any help would be appreciated, thank you.

Answer 1

Could be because array is not defined in the code, at least in the part of code is visible here. Try invert the condition, maybe will works then.

(e.which) ? e.which : e.keyCode

Other idea is use the code below before use e in the previous comparisons:

 if (window.event){
   e = window.event.keyCode;}
   else if (event.charCode) {
    e = event.charCode;}
   else if (event.which){
   e = event.which; } 
 }