gulp-concat twice the content

Question

That's a weird thing for me, i have a task to concat my .js files and then uglify them with a watcher, but the concat task just twice the content in every call...

Here is my gulpfile:

'use strict';

let gulp        = require('gulp');
let stylus      = require('gulp-stylus');
let sourcemaps  = require('gulp-sourcemaps');
let concat      = require('gulp-concat');
let uglify      = require('gulp-uglify');
let plumber     = require('gulp-plumber');
let bootstrap   = require('bootstrap-styl');
let rupture     = require('rupture');
let copy        = require('gulp-copy2');

/*
  Prepare the paths
*/
let base = './theme';
let themeName = 'own-theme';

let paths = {
  stylus    : `${base}/${themeName}/css`,
  js        : `${base}/${themeName}/js`,
  vendor    : `${base}/${themeName}/js/vendor`
}

/*
  Stylus compile
*/
gulp.task('stylus-compile', () => {
  return gulp.src([`${paths.stylus}/dev/*.styl`, `${paths.stylus}/!**/_*.styl`])
    .pipe(plumber())
    .pipe(stylus({
      use: [bootstrap(), rupture()],
      compress: true
    }))
    .pipe(sourcemaps.write('./'))
    .pipe(gulp.dest(`${paths.stylus}`));
});

/*
  Get the bootstrap-styl js files and concat/uglify them
*/

gulp.task('bootstrap-build', () => {
  return gulp.src([
    'node_modules/bootstrap-styl/js/transition.js',
    'node_modules/bootstrap-styl/js/alert.js',
    'node_modules/bootstrap-styl/js/button.js',
    'node_modules/bootstrap-styl/js/carousel.js',
    'node_modules/bootstrap-styl/js/collapse.js',
    'node_modules/bootstrap-styl/js/dropdown.js',
    'node_modules/bootstrap-styl/js/modal.js',
    'node_modules/bootstrap-styl/js/tooltip.js',
    'node_modules/bootstrap-styl/js/popover.js',
    'node_modules/bootstrap-styl/js/scrollspy.js',
    'node_modules/bootstrap-styl/js/tab.js',
    'node_modules/bootstrap-styl/js/affix.js'
  ])
  .pipe(sourcemaps.init())
  .pipe(concat('bootstrap.min.js'))
  .pipe(uglify())
  .pipe(sourcemaps.write('./'))
  .pipe(gulp.dest(`${paths.vendor}`));

});

/*
  Get the js assets from NPM
*/
gulp.task('js-copy', () => {
  let dirs = [
    { src: 'node_modules/jquery/dist/jquery.min.js', dest: `${paths.vendor}/jquery.min.js` },
    { src: 'node_modules/sweet-scroll/sweet-scroll.min.js', dest: `${paths.vendor}/sweet-scroll.min.js` }
  ]
    return copy(dirs);
});

/*
  Concat/Uglify the JS files
*/
gulp.task('js-build', () => {
return gulp.src(`${paths.js}/*.js`)
  .pipe(sourcemaps.init())
  .pipe(concat('site.min.js'))
  // .pipe(uglify())
  .pipe(sourcemaps.write('./'))
  .pipe(gulp.dest(`${paths.js}`));
})

/*
  Watch
*/
gulp.task('watch', () => {
  gulp.watch(`${paths.js}/*.js`, ['js-build']);
  gulp.watch(`${paths.stylus}/dev/*.styl`, ['stylus-compile']);
});

gulp.task('default', ['bootstrap-build', 'js-copy', 'watch']);

The bootstrap-build task don't twice the content no matter how many times you call the task, but the js-build does.

Here are the test separated scripts to concat and the results:

File 1:

(function() {

  console.log("oh!")
  console.log("uh!")

}).call(this);

File 2:

(function() {
  console.log("hey")
}).call(this);

Concated file(uh, oh file re-saved after the watcher was fired):

(function() {

  console.log("oh!")
  console.log("uh!")

}).call(this);
(function() {

  console.log("oh!")
  console.log("uh!")

}).call(this);
(function() {
  console.log("hey")
}).call(this);
//# sourceMappingURL=site.min.js.map

(function() {
  console.log("hey")
}).call(this);
//# sourceMappingURL=site.min.js.map

In every re-save, the concat twice the content... i really don't get the problem. Any idea?

Thanks in adnvance.

Answer 1

The reason your bootstrap-build works is because it places the resulting bootstrap.min.js in a different folder than the source files.

Your js-build task however concatenates all .js files in your path.js folder and places the resulting site.min.js in that same folder.

That means when first running js-build the files file1.js and file2.js are concatenated into site.min.js . On a second run the files file1.js , file2.js and site.min.js are concatenated into site.min.js . Every time you run your js-build task your site.min.js grows.

What you need to do is exclude site.min.js from being concatenated with the other files:

gulp.task('js-build', () => {
  return gulp.src([
      `${paths.js}/*.js`,
      `!${paths.js}/site.min.js`
    ])
    .pipe(sourcemaps.init())
    .pipe(concat('site.min.js'))
    // .pipe(uglify())
    .pipe(sourcemaps.write('./'))
    .pipe(gulp.dest(`${paths.js}`));
})