AoC-2017-day9.js

let data = require("fs").readFileSync("day9-input.txt", "UTF-8");

let garbage = 0;
let total = 0;
let canceled = false;
let ignore = false;
let depth = 0;

data.split("").forEach(char => {
  if (ignore) {
    if (canceled) {
      canceled = false;
      return;
    }

    if (char === ">") {
      ignore = false;
      return;
    }

    if (char === "!") {
      canceled = true;
      return;
    }

    garbage++;
    return;
  }

  switch (char) {
    case "<":
      ignore = true;
      break;
    case "{":
      depth++;
      break;
    case "}":
      total += depth;
      depth--;
      break;
  }
});

console.log("Part 1:", total);
console.log("Part 2:", garbage);