mathjs/docs/command_line_debugging.md

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser and offers an integrated solution to work with numbers, big numbers, complex numbers, units, and matrices.

# Command Line Debugging

For debugging purposes, `bin/repl.js` provides a REPL (Read Evaluate Print Loop)
for interactive testing of mathjs without having to build new build files after every
little change to the source files. You can either start it directly (`./repl.js`) or
via node (`node repl.js`).

You can exit using either [ctrl]-[C] or [ctrl]-[D].

```bash
$ ./repl.js 
> math.parse('1+1')
{ op: '+',
  fn: 'add',
  args: 
   [ { value: '1', valueType: 'number' },
     { value: '1', valueType: 'number' } ] }
> 
```