GitHub project with explanation here

Create small JSFuck code

Compiler tested (31.08.2020) on Chrome 84, Firefox 79, Safari 13 and node.js 12.16.1

1 kB of input code gives 16-32kB (usually ~24kB) output plus constant ~23kB bootstrap code

Example from here (31.08.2020: jsfuck.com produce: 247545 chars, Xchars.js produce 72658 chars)