day-1-part-2.js

const position = { x: 0, y: 0 }

// left up right down
const Dir = [ [0, 3, 1, {x: -1, y: 0}], [1, 0, 2, {x: 0, y: 1}], [2, 1, 3, {x: 1, y: 0}], [3, 2, 0, {x: 0, y: -1}]]

const positionHistory = []

let currentDirectionIndex = 1

function move(input) {
    const dir = input[0]
    const steps = input.substr(1)
    currentDirectionIndex = Dir.find(direction => Dir[currentDirectionIndex][dir === 'L' ? 1 : 2] === direction[0])[0]
    let currentDirection = Dir[currentDirectionIndex]

    let deltaX = currentDirection[3].x
    let deltaY = currentDirection[3].y

    if (deltaX != 0) {
        for (let i = 0; i < steps; i++) {
            position.x += deltaX
            positionHistory.push({x: position.x, y: position.y})
        }
    }

    if (deltaY != 0) {
        for (let i = 0; i < steps; i++) {
            position.y += deltaY
            positionHistory.push({x: position.x, y: position.y})
        }
    }

    found = checkHistory()
}

var found
function checkHistory() {

    let temp = []
    for (let point of positionHistory) {
        for (let tempPoint of temp) {
            if (tempPoint.x === point.x && tempPoint.y === point.y)
                return point
        }
        temp.push(point)
    }
    return null
}

const inputString = "L5, R1, L5, L1, R5, R1, R1, L4, L1, L3, R2, R4, L4, L1, L1, R2, R4, R3, L1, R4, L4, L5, L4, R4, L5, R1, R5, L2, R1, R3, L2, L4, L4, R1, L192, R5, R1, R4, L5, L4, R5, L1, L1, R48, R5, R5, L2, R4, R4, R1, R3, L1, L4, L5, R1, L4, L2, L5, R5, L2, R74, R4, L1, R188, R5, L4, L2, R5, R2, L4, R4, R3, R3, R2, R1, L3, L2, L5, L5, L2, L1, R1, R5, R4, L3, R5, L1, L3, R4, L1, L3, L2, R1, R3, R2, R5, L3, L1, L1, R5, L4, L5, R5, R2, L5, R2, L1, L5, L3, L5, L5, L1, R1, L4, L3, L1, R2, R5, L1, L3, R4, R5, L4, L1, R5, L1, R5, R5, R5, R2, R1, R2, L5, L5, L5, R4, L5, L4, L4, R5, L2, R1, R5, L1, L5, R4, L3, R4, L2, R3, R3, R3, L2, L2, L2, L1, L4, R3, L4, L2, R2, R5, L1, R2"

const commands = inputString.split(", ")

for (const command of commands) {
    move(command)
    if (found) break
}

if (found)
    console.log("Distance: " + (Math.abs(found.x) + Math.abs(found.y)))
else
    console.log("Aww; no intersection")