peak.js

var substruct_size_limit = 2,
      left_side = 0,
      right_side = 1,
      operation_counter = 0,
      lolarr = [];

function algo1_brute_force(arr) {
  var max = 0;
  for (var i = 0; i < arr.length; i += 1) {
    operation_counter += 1;
    if (arr[i] >= max) max = arr[i];
  }
  return max;
}

function algo3_dac(arr) {
  operation_counter += 1;
  var mid = arr.length / 2,
      mid_to_the_left = mid - 1,
      mid_to_the_right = mid + 1;
    if (arr.length === substruct_size_limit) {
      return arr[left_side] > arr[right_side] ? arr[left_side] : arr[right_side];
    }
    var mid = parseInt(arr.length / 2);
    if (arr[mid] < arr[mid - 1]) {
      return algo3_dac(arr.slice(0, mid - 1))
    } else if (arr[mid] < arr[mid + 1]) { 
      return algo3_dac(arr.slice(mid, arr.len));
    } else {
      return arr[left_side]
    }
}

for (var x = 0; x < 1000000; x += 1) {
  lolarr.push(x);
}

function run(fn) {
  console.log("\n");
  console.log("Runtime evaluation for: " + fn.name);
  var new_starttime = +Date.now();
  console.log("Max: " + fn(lolarr));
  var new_endtime = +Date.now();
  console.log("Operation Counter: " + operation_counter);
  console.log('Time took: ' + ((new_endtime - new_starttime) / 100) + ' seconds');
  console.log("Operation Counter: " + operation_counter);
  operation_counter = 0;
}

run(algo3_dac);
run(algo1_brute_force);