module.exports = function (cb, dir, ext) {


var fs = require("fs");

var path = require("path");

fs.readdir(dir, function callback(err, list) {
    if (err) {
        return cb(err, null);
    }

    else {
        var l = list.length;
        var i = 1;
        var arr = [];
        for (i = 0; i < l; i++) {

            if (path.extname(list[i]) === "." + ext) {

                arr.push(list[i])
            }
        }
    }
    return cb(null, arr);
})