npm-shrinkwrap - programmatically generate package shrinkwrap file
npm.commands.shrinkwrap(args, [silent,] callback)
This acts much the same ways as shrinkwrapping on the command-line.
This command does not take any arguments, but ´args´ must be defined. Beyond that, if any arguments are passed in, npm will politely warn that it does not take positional arguments.
If the ´silent´ parameter is set to true, nothing will be output to the screen, but the shrinkwrap file will still be written.
Finally, ´callback´ is a function that will be called when the shrinkwrap has been saved.