function indexSearch(list, element) {
let currentIndex,
currentElement,
minIndex = 0,
maxIndex = list.length - 1;
while (minIndex <= maxIndex) {
currentIndex = Math.floor(minIndex + maxIndex) / 2;
currentElement = list[currentIndex];
if (currentElement === element) {
return currentIndex;
}
if (currentElement < element) {
minIndex = currentIndex + 1;
}
if (currentElement > element) {
maxIndex = currentIndex - 1;
}
}
return -1;
}