A non-Python developer's attempt at a SublimeText 2 plugin.

multilinejs.py

import sublime
import sublime_plugin
import re

'''
SublimeText 2 plugin to convert selections (or the entire document) to a
JavaScript multiline string using the [].join('\n') idiom.

Given a document like:

    line one
    line two

It will create:

    var FIXME = [
      'line one',
      'line two'
    ].join('\n');

Keybind this by adding something like the following to
`Packages/User/Default (<platform>).sublime-keymap`

    { "keys": ["ctrl+shift+c"], "command": "multiline_js" }
'''

class MultilineJsCommand(sublime_plugin.TextCommand):
  def run(self, edit, **args):
    if self.view.sel()[0].empty():
      # no selections, so create a selection of the entire document
      self.view.sel().add(sublime.Region(0, self.view.size()))

    # wrap a string in single quotes
    def quote(str):
      return re.sub(r"(\s*)(.+)(\s*)", r"  \1'\2'\3", str)

    for sel in self.view.sel():
      str = self.view.substr(sel)

      # capture leading spaces for use later when injecting the new text
      m = re.match(r"\s*", str)
      if m:
        lead = m.group()
      else:
        lead = ''

      fixed = '\n' + ',\n'.join(map(quote, str.splitlines())) + '\n'

      js = lead + 'var FIXME = [' + fixed + lead + '].join(\'\\n\');'

      self.view.replace(edit, sel, js)