Searches for a triplet of values in an array that sum to the target value. Returns null if such a triplet doesn't exist. Takes O(n^2) time.

tiple.js

function threeTuple( array, target ) {
  if (isNaN(target)){return null;}
  array.sort();
  for (var i = 0; i < array.length; i++) {
    var j = i+1;
    var k = array.length - 1; // start at the end of the array
    while(k > j) {
      summation = array[i] + array[j] + array[k];
      if (summation === target) {return [i,j,k];}
      if (summation > target) {k--;}
      if (summation < target) {j++;}
    }
  }
  return null;
}

// tests
var set = [0,1,2,3,-4,5];
var testTargets = [2, 4, 100, "100 million"]
for (var i = 0; i < testTargets.length; i++){
  var result = threeTuple(set, testTargets[i]);
  print((result === null) ? "No dice." : [set[result[0]],set[result[1]],set[result[2]]]);
}