devict.org Code Challenge - Partition On

partitionon.js

function partitionOn(pred, items) {
  var sp_idx = 0;
  for(var i in items) {
    if(!pred(items[i])) {
      // If the predicate is false, move it to sp_idx, otherwise, leave it.
      items.splice((sp_idx++), 0, items.splice(i, 1)[0]);
    }
  }
  return sp_idx;
}