var arr = new Array();
arr[0] = 100;
arr[1] = 0;
arr[2] = 50;

Array.prototype.max = function() {
  return Math.max.apply(null, this)
}

Array.prototype.min = function() {
  return Math.min.apply(null, this)
}

var min = Math.min.apply(null, arr),
    max = Math.max.apply(null, arr);

To find the Maximum value in Array Use Below

 var max_of_array = Math.max.apply(Math, array);