Inline a source map file into the JavaScript source file as a data URI

_README.md

Description:

A quick script to inline / inject a source map file into the JavaScript source file.

Use case: Sometimes you have a script.js and a script.js.map file, and you'd prefer to inline the source map as a data URI directly into the script.js file.

NOTE: Modifies the script.js file in-place

Usage:

inline_source_map.rb <script.js>

• script.js must end with //# sourceMappingURL=some.js.map
• Modifies script.js in-place, injecting the base-64 encoded data URI in place of the some.js.map reference

inline_source_map.rb

#!/usr/bin/env ruby

require 'pathname'
require 'base64'

js_file = ARGV[0]

if (js_file==nil) then
  puts "Usage: inline_source_map.rb <script.js>"
  puts " - script.js is expected to have a trailing //# sourceMappingURL=file.map"
  exit 1
end

js_file = Pathname.new(File.join(Dir.pwd, js_file)).cleanpath.to_s
js_dir = File.dirname(js_file)

puts "Reading #{ js_file }"
js = File.read(js_file)
map_file = js.match(/\/\/# sourceMappingURL=([\w.\/]+\.map)\s*$/)
if (map_file && map_file[1]) then
  map_content = File.read(File.join(js_dir, map_file[1]))
  encoded = Base64::encode64(map_content).gsub(/\s/, "")
  js.sub!(/\/\/# sourceMappingURL=([\w.\/]+\.map)\s*$/, "//# sourceMappingURL=data:application/json;charset=utf-8;base64,#{ encoded }")
  puts "Writing #{ js_file } (adding ~#{ encoded.length } bytes)"
  File.open(js_file, "w") { |f| f.puts js }
else
  puts "Error: did not find trailing //# sourceMappingURL=file.map"
  exit 1
end