Concatenating files

npm install --save-dev gulp gulp-concat gulp-rename gulp-uglify gulp-uglifycss

var gulp = require('gulp');
var gulp_concat = require('gulp-concat');
var gulp_rename = require('gulp-rename');
var gulp_uglify = require('gulp-uglify');
var uglifycss = require('gulp-uglifycss');

var destDir = './public/assets/dist/'; //or any folder inside your public asset folder
var tempDir = './public/assets/temp/'; //any place where you want to store the concatenated, but unuglified/beautified files
//To concat and Uglify All JS files in a particular folder
gulp.task('js-uglify', function(){
    return gulp.src(['./public/js/**/*.js','./public/assets/js/*.js']) //Use wildcards to select all files in a particular folder or be specific
        .pipe(gulp_concat('concat.js')) //this will concat all the files into concat.js
        .pipe(gulp.dest(tempDir)) //this will save concat.js in a temp directory defined above
        .pipe(gulp_rename('uglify.js')) //this will rename concat.js to uglify.js
        .pipe(gulp_uglify()) //this will uglify/minify uglify.js
        .pipe(gulp.dest(destDir)); //this will save uglify.js into destination Directory defined above
});
//To Concat and Uglify all CSS files in a particular folder
gulp.task('css-uglify', function () {
  gulp.src('./public/assets/css/*.css') //Use wildcards to select all files in a particular folder or be specific
  .pipe(gulp_concat('concat.css')) //this will concat all the source files into concat.css
        .pipe(gulp.dest(tempDir)) //this will save concat.css into a temp Directory
        .pipe(gulp_rename('uglify.css')) //this will rename concat.css into uglify.css, but will not replace it yet.
    .pipe(uglifycss({
      "maxLineLen": 80,
      "uglyComments": true
    })) //uglify uglify.css file
    .pipe(gulp.dest(destDir)); //save uglify.css
});

gulp js-uglify
gulp css-uglify