Question

I’m probably going about this in entirely the wrong way, but pseudocode-wise, this is what I’d like to do:

ranges = new Array([0 - 400] = 'dog',
               [401 - 1000] = 'cat',
               [1001 - 1233] = 'rat');

alert(ranges[243]);

and magically get ‘dog’ pop up on my screen. Now, I’m well aware you can’t do something that simple, but I have absolutely no idea how to do something like this (without looping through an array, performing a > and < on a value etc..)

Any ideas? 🙂

Answer 1

This one is very simple and straightforward – though it assumes that you don’t want “holes” in your ranges. No error handling in this example, but essentially you just need to pass upper bounds, lower bounds are implicit.

function test() {
    var array = MakeRangeArray([500,1000,2000], ['dog', 'cat', 'rat']);

    alert (array[243]);
    alert (array[500]);
    alert (array[501]);
}

function MakeRangeArray(upperBounds, values) {
   var rangeArray = new Array(upperBounds[upperBounds.length-1]);

   var idx = 0;
   for (var i=0; i < rangeArray.length; i++) {
      if (i > upperBounds[idx]) {
        idx++;
      }
      rangeArray[i] = values[idx];
   }
   return rangeArray;
}