day2.js

const text = `1,0,0,3,1,1,2,3,1,3,4,3,1,5,0,3,2,6,1,19,2,19,9,23,1,23,5,27,2,6,27,31,1,31,5,35,1,35,5,39,2,39,6,43,2,43,10,47,1,47,6,51,1,51,6,55,2,55,6,59,1,10,59,63,1,5,63,67,2,10,67,71,1,6,71,75,1,5,75,79,1,10,79,83,2,83,10,87,1,87,9,91,1,91,10,95,2,6,95,99,1,5,99,103,1,103,13,107,1,107,10,111,2,9,111,115,1,115,6,119,2,13,119,123,1,123,6,127,1,5,127,131,2,6,131,135,2,6,135,139,1,139,5,143,1,143,10,147,1,147,2,151,1,151,13,0,99,2,0,14,0`;

let instructions = text.split(",").map(instruction => parseInt(instruction));
instructions[1] = 53;
instructions[2] = 98;
let currentInstruction = 0;
let hitEndOpCode = false;

const add = (param1, param2, destination) => {
  instructions[destination] = instructions[param1] + instructions[param2];
}

const multiply = (param1, param2, destination) => {
  instructions[destination] = instructions[param1] * instructions[param2];
}

const runInstruction = () => {
  const opCode = instructions[currentInstruction];
  const param1 = instructions[currentInstruction + 1];
  const param2 = instructions[currentInstruction + 2];
  const destination = instructions[currentInstruction + 3];

  switch (opCode) {
    case 1:
      add(param1, param2, destination);
      break;
    case 2:
      multiply(param1, param2, destination);
      break;
    case 99:
      hitEndOpCode = true;
      break;
    default:
      console.log("oh no");
  }

  currentInstruction += 4;
}

while (currentInstruction < instructions.length && !hitEndOpCode) {
  runInstruction();
}

console.log(instructions[0]);