I'd like to find all *.html files in src folder and all its sub folders using nodejs. What is the best way to do it?

var folder = '/project1/src';
var extension = 'html';
var cb = function(err, results) {
   // results is an array of the files with path relative to the folder
   console.log(results);

}
// This function is what I am looking for. It has to recursively traverse all sub folders. 
findFiles(folder, extension, cb);

I think a lot developers should have great and tested solution and it is better to use it than writing one myself.