block6.ts

import { reactive, watch } from '@vue/runtime-core'

// % in Javascript is remainder operator, e.g. -1 % 5 gives -1.
// The following is an implementation for modulus.
const mod = (x: number, y: number) => ((x % y) + y) % y

const MAX_ROAD_LENGTH = 10

const car = reactive({
  position: 0,
  speed: 2,
})

setInterval(() => {
  car.position = mod(car.position + car.speed, MAX_ROAD_LENGTH)
}, 1000)

watch(() => {
  const road = [...'_'.repeat(MAX_ROAD_LENGTH)]
  road[car.position] = '🚗'

  console.clear()
  console.log(road.reverse().join(''))
})