scripts.js

var gulp = require('gulp'),
    path = require('path'),
    folder = require('gulp-folders'),
    gulpIf = require('gulp-if'),
    insert = require('gulp-insert'),
    concat = require('gulp-concat'),
    uglify = require('gulp-uglify'),
    notify = require('gulp-notify'),
    rename = require('gulp-rename'),
    source_folder = 'source/js',
    destination_folder = 'deploy/j',
    rename_serviceworker = rename({
        dirname: "../"
    });

gulp.task('scripts', folder(source_folder, function(folder){
    
    function createErrorHandler( name )
    {
	    return function (err) {
	        console.error('Error from ' + name + ' in compress task', err.toString());
	    };
    }

    return gulp.src(path.join(source_folder, folder, '*.js'))
        .pipe(concat(folder + '.js'))
        .pipe(insert.prepend('(function(window,document){'))
        .pipe(insert.append('}(this,this.document));'))
        .pipe(insert.transform(function(contents, file){
            // insert a build time variable
            var build_time = (new Date()).getTime() + '';
            return contents.replace( '{{BUILD_TIME}}', build_time );
         }))
        .pipe(gulpIf(folder=='serviceworker',rename_serviceworker))
        .pipe(gulp.dest(destination_folder))
        .pipe(gulpIf(folder!='serviceworker',uglify().on('error', createErrorHandler('uglify'))))
        .pipe(gulpIf(folder!='serviceworker',rename({suffix: '.min'})))
        .pipe(gulpIf(folder!='serviceworker',gulp.dest(destination_folder)))
        .pipe(notify({ message: 'Scripts task complete' }));
    
}));