There are several exposed methods on readline that are not documented:

• readline.getStringWidth()
• readline.isFullWidthCodePoint()
• readline.stripVTControlCharacters()
• readline.emitKeypressEvents()

They should IMHO either be documented or made internal. Preferably the latter.

Most of these are already modules on npm anyways:

• getStringWidth → string-width
• isFullWidthCodePoint → is-fullwidth-code-point
• stripVTControlCharacters → strip-ansi