Holy moly! Quines in javascript

Holy moly! Quines in javascript

March 14, 2021


Let's build a quine using javascript. but wait a minute what is QUINE ???

A Quine the name came from the book Gödel, Escher, Bach in honor of philosopher Willard Van Orman Quine (1908–2000) by Douglas Hofstadter and it significate a computer program that takes no input and can print its own source code. These programs called "self-replicating programs" or "self-reproducing programs".

The behavior of this program it's can be used to reproduce new programs in a given ecosystem think about a Worm (computer virus) that can reproduce itself through network devices.

Imagine combining quining with AI :-o


Mainly quines problems (as I know) are used as challenge or fun in computer science and if you want to make a quine in any programming language you need to fit 3 rules:

  • Quine can't get any input or args

  • You most achieve quining without using IO (read from the disk) so something like this isn't allowed

console.log(require('fs').readFileSync('./index.js',{encoding:'utf8', flag:'r'}))
  • You quine need to have at least 1 character because technically an empty program is a quine that print it's own source code YEY CRAZY

Advanced Quines

What we described here is a "vanilla" Quine but we have more advanced ones, grab a set:


is a program that it's valid in more than one programing language at the same time and in each one, it's printing its source code.

Ouroboros quine

It's ruby program that's =(create)=> rust program that's =(create)=> scala program ... and after 128 languages it's create a the original ruby program. This beautiful beast is created by japanase programmer Yusuke Endoh (ruby core language contributor); Check this repo for more information.

Hacking time

As I use javascript I'll try to build one using javascript basically I need to use a template literals and stringify the main function and put it as variable in the string template and what's makes my task relatively easy is all javascript functions have a .toString() method that is fired automatically when you try to treat a function as a string (print, concat ...); plus for a simplicity reason I will use a IIFE.

(function q(){
  return '('+ q.toString() +')()'

and for the sake of geekiness

$=_=> `$=${$};$()`;$()


Written by Abderrahim SOUBAI-ELIDRISI full stack JavaScript developer. Interested in web Technologies & cloud computing & problem solving. Follow him on twitter