Search module in JavaScript
Rather than creating a function named My_module, and assigning it to module.exports, you can just directly assign a function to module.exports, like this:

module.exports = function() {
    ...
}


Secondly, why are you ending all your functions and variables in My_module with an underscore, _? It doesn't do anything, and if it's not serving a real naming purpose, it can be removed.