Using Gulp to Concatenate and Uglify files

My gulp file produces a final compiled-bundle-min.js, hope this helps someone.

//Gulpfile.js

var gulp = require("gulp");
var watch = require("gulp-watch");

var concat = require("gulp-concat");
var rename = require("gulp-rename");
var uglify = require("gulp-uglify");
var del = require("del");
var minifyCSS = require("gulp-minify-css");
var copy = require("gulp-copy");
var bower = require("gulp-bower");
var sourcemaps = require("gulp-sourcemaps");

var path = {
    src: "bower_components/",
    lib: "lib/"
}

var config = {
    jquerysrc: [
        path.src + "jquery/dist/jquery.js",
        path.src + "jquery-validation/dist/jquery.validate.js",
        path.src + "jquery-validation/dist/jquery.validate.unobtrusive.js"
    ],
    jquerybundle: path.lib + "jquery-bundle.js",
    ngsrc: [
        path.src + "angular/angular.js",
         path.src + "angular-route/angular-route.js",
         path.src + "angular-resource/angular-resource.js"
    ],
    ngbundle: path.lib + "ng-bundle.js",

    //JavaScript files that will be combined into a Bootstrap bundle
    bootstrapsrc: [
        path.src + "bootstrap/dist/js/bootstrap.js"
    ],
    bootstrapbundle: path.lib + "bootstrap-bundle.js"
}

// Synchronously delete the output script file(s)
gulp.task("clean-scripts", function (cb) {
    del(["lib","dist"], cb);
});

//Create a jquery bundled file
gulp.task("jquery-bundle", ["clean-scripts", "bower-restore"], function () {
    return gulp.src(config.jquerysrc)
     .pipe(concat("jquery-bundle.js"))
     .pipe(gulp.dest("lib"));
});

//Create a angular bundled file
gulp.task("ng-bundle", ["clean-scripts", "bower-restore"], function () {
    return gulp.src(config.ngsrc)
     .pipe(concat("ng-bundle.js"))
     .pipe(gulp.dest("lib"));
});

//Create a bootstrap bundled file
gulp.task("bootstrap-bundle", ["clean-scripts", "bower-restore"], function     () {
    return gulp.src(config.bootstrapsrc)
     .pipe(concat("bootstrap-bundle.js"))
     .pipe(gulp.dest("lib"));
});


// Combine and the vendor files from bower into bundles (output to the Scripts folder)
gulp.task("bundle-scripts", ["jquery-bundle", "ng-bundle", "bootstrap-bundle"], function () {

});

//Restore all bower packages
gulp.task("bower-restore", function () {
    return bower();
});

//build lib scripts
gulp.task("compile-lib", ["bundle-scripts"], function () {
    return gulp.src("lib/*.js")
        .pipe(sourcemaps.init())
        .pipe(concat("compiled-bundle.js"))
        .pipe(gulp.dest("dist"))
        .pipe(rename("compiled-bundle.min.js"))
        .pipe(uglify())
        .pipe(sourcemaps.write("./"))
        .pipe(gulp.dest("dist"));
});

It turns out that I needed to use gulp-rename and also output the concatenated file first before 'uglification'. Here's the code:

var gulp = require('gulp'),
    gp_concat = require('gulp-concat'),
    gp_rename = require('gulp-rename'),
    gp_uglify = require('gulp-uglify');

gulp.task('js-fef', function(){
    return gulp.src(['file1.js', 'file2.js', 'file3.js'])
        .pipe(gp_concat('concat.js'))
        .pipe(gulp.dest('dist'))
        .pipe(gp_rename('uglify.js'))
        .pipe(gp_uglify())
        .pipe(gulp.dest('dist'));
});

gulp.task('default', ['js-fef'], function(){});

Coming from grunt it was a little confusing at first but it makes sense now. I hope it helps the gulp noobs.

And, if you need sourcemaps, here's the updated code:

var gulp = require('gulp'),
    gp_concat = require('gulp-concat'),
    gp_rename = require('gulp-rename'),
    gp_uglify = require('gulp-uglify'),
    gp_sourcemaps = require('gulp-sourcemaps');

gulp.task('js-fef', function(){
    return gulp.src(['file1.js', 'file2.js', 'file3.js'])
        .pipe(gp_sourcemaps.init())
        .pipe(gp_concat('concat.js'))
        .pipe(gulp.dest('dist'))
        .pipe(gp_rename('uglify.js'))
        .pipe(gp_uglify())
        .pipe(gp_sourcemaps.write('./'))
        .pipe(gulp.dest('dist'));
});

gulp.task('default', ['js-fef'], function(){});

See gulp-sourcemaps for more on options and configuration.

UPDATE - FEB 2022

These days, it may be easier for you to handle build tasks using Gulp4 and Async/Await functionality:

// gulpfile.js

const fs = require('fs/promises');
const concat = require('concat');
const uglify = require('uglify-js');

let files_arr = ['file1.js', 'file2.js', 'file3.js'];

async function myGulpTask()
{
    var concat_str,
        uglify_str
    ;

    // concat content
    concat_str = await concat(files_arr);

    // save to file
    await fs.writeFile('concat.js', concat_str, 'utf8');

    // uglify content
    uglify_str = await uglify.minify(concat_str, {mangle:false}).code;

    // save to file
    await fs.writeFile('uglify.js', uglify_str, 'utf8');
}

module.exports = {
    myTask: myGulpTask
};

Then from the CLI:

gulp myTask