NumberOfPeopleInTheBus.js

/**
 * Description:
 *
 * There is a bus moving in the city which takes and drops
 * some people at each bus stop.
 *
 * You are provided with a list
 * (or array) of integer pairs. Elements of each pair
 * represent the number of people that get on the bus
 * (the first item) and the number of people that get
 * off the bus (the second item) at a bus stop.
 *
 * Your task is to return the number of people who are
 * still on the bus after the last bus stop (after the last array).
 * Even though it is the last bus stop, the bus might not be
 * empty and some people might still be inside the bus, they
 * are probably sleeping there :D
 *
 * Take a look on the test cases.
 *
 * Please keep in mind that the test cases
 * ensure that the number of people in the bus
 * is always >= 0. So the returned integer can't be negative.
 *
 * The second value in the first pair in the array is 0,
 * since the bus is empty in the first bus stop.
 *
 * Kata URL: https://www.codewars.com/kata/5648b12ce68d9daa6b000099
 *
 * @param {*} busStops
 * @returns Number of people still inside the bus after the last bus stop
 */

var number = function (busStops) {
  let count = 0;
  busStops.forEach((element) => {
    count = count + element[0] - element[1];
  });
  return count;
};