slashes-interpreter.js

const fs = require("fs");
const code = fs.readFileSync("program.txt", "utf8");

function run(code) {
  let state = 0;
  let replacement = { from: "", to: "" };
  let escaping = false;
  let output = "";
  while (code.length > 0) {
    const char = code[0];
    code = code.slice(1);
    if (char === "/" && !escaping) {
      state = (state+1) % 3;
      if (state === 0) {
        code = code.replaceAll(replacement.from, replacement.to);
        replacement = { from: "", to: "" };
      }
    } else if (char === "\\" && !escaping) {
      escaping = true;
    } else if (state === 0) {
      output += char;
      escaping = false;
    } else if (state === 1) {
      replacement.from += char;
      escaping = false;
    } else if (state === 2) {
      replacement.to += char;
      escaping = false;
    }
  }
  console.log(output);
}

run(code);