bs-findinarray.js

function findInArray(items, value, predicate) {
  predicate = predicate || contains;

  var min = 0;
  var max = items.length - 1;
  var mid = Math.floor(items.length / 2);
  var foundIndex = false;

  while (foundIndex === false) {
    if (predicate(items, value, min, mid)) {
      foundIndex = items[min] === value ? min : items[mid] === value ? mid : false;
      max = mid;
      mid = Math.floor(mid / 2);
    }
    else if (predicate(items, value, mid, max)) {
      foundIndex = items[mid] === value ? mid : items[max] === value ? max : false;
      min = mid;
      mid = Math.floor((max - min) / 2) + mid;
    }
    else {
      return;
    }
  }

  return foundIndex;
};

function contains(items, value, min, max) {
  return value >= items[min] && value <= items[max];
}