compress js

gulpfile.js

// install
// npm i gulp-concat gulp-uglify
var concat = require('gulp-concat');
var uglify = require('gulp-uglify');

// concat and clean js
gulp.task('compress:js', function () {
    var jsjq = './app/js/jquery.min.js';
    var jscore = './app/js/core.js';
    var jsplug = './app/js/plugins.js';
    var jsscript = './app/js/scripts.js';

    return gulp.src([jsjq, jscore, jsplug, jsscript])
        .pipe(concat('scripts.js'))
        .pipe(uglify())
        .pipe(gulp.dest('./dist/js'));
});