get number value to store in array and do loop to process and choose from array.

choose_even_in_array.htm

<script>
var ar = new Array();
ar[0] = window.prompt("put a number"); // 3
ar[1] = window.prompt("put a number"); // 4
ar[2] = window.prompt("put a number"); // 5
ar[3] = window.prompt("put a number"); // 6
ar[4] = window.prompt("put a number"); // 7
window.alert(ar.length); // 5
var keep = "";
for (idx in ar) { keep += ar[idx]; }
window.alert(keep); // 34567
keep = "";
for (i = 0; i < ar.length; i++) {
  if(ar[i] % 2 == 0) { keep += ar[i]; } // >0
}
console.log(keep); // 46 , firefox:ctrl-shift-c , chrome:ctrl-shift-i
// http://www.w3schools.com/js/tryit.asp?filename=tryjs_loop_for
</script>