Yii2 assets and gulp - gulp

Question

I learn Yii2 and tried to use gulp with it in way like described here. I created gulp config with following content:
var gulp = require('gulp');
var uglify = require('gulp-uglify');
var cssMin = require('gulp-css');
var rename = require('gulp-rename');
var minimist = require('minimist');
var options = minimist(process.argv.slice(2), {string: ['src', 'dist']});
var destDir = options.dist.substring(0, options.dist.lastIndexOf("/"));
var destFile = options.dist.replace(/^.*[\\\/]/, '');
// Use `compress-js` task for JavaScript files 
gulp.task('compress-js', function () {
    return gulp.src(options.src)
        .pipe(uglify())
        .pipe(rename(destFile))
        .pipe(gulp.dest(destDir))
});
// Use `compress-css` task for CSS files
gulp.task('compress-css', function () {
    return gulp.src(options.src)
        .pipe(cssMin())
        .pipe(rename(destFile))
        .pipe(gulp.dest(destDir))
});
I use this file for my bundle:
<?php
namespace app\assets;
use yii\web\AssetBundle;
class AppAsset extends AssetBundle
{
    public $basePath = '#webroot';
    public $baseUrl = '#web';
    public $css = [
        'css/site.css',
    ];
    public $js = [
    ];
    public $jsOptions = [
        'position' => \yii\web\View::POS_HEAD
    ];
    public $depends = [
        'yii\web\YiiAsset',
        'yii\bootstrap\BootstrapAsset',
    ];
}
And, after all, I use this config for asset command
<?php
Yii::setAlias('#webroot', str_replace('\\', '/',  __DIR__) . '/web');
Yii::setAlias('#web', '/');
return [
    'jsCompressor' => 'gulp compress-js --gulpfile gulpfile.js --src {from} --dist {to}',
    'cssCompressor' => 'gulp compress-css --gulpfile gulpfile.js --src {from} --dist {to}',
    'bundles' => [
        'app\assets\AppAsset'
    ],
    'targets' => [
        'all' => [
            'class' => 'yii\web\AssetBundle',
            'basePath' => '#webroot/assets',
            'baseUrl' => '#web/assets',
            'js' => 'combined-{hash}.js',
            'css' => 'combined-{hash}.css',
            'depends' => [
            ],
        ],
    ],
    // Asset manager configuration:
    'assetManager' => [
        'basePath' => '#webroot/assets',
        'baseUrl' => '#web/assets',
        'linkAssets' => true
    ],
];
But, when I try to run php yii asset assets-config.php config/assets-prod.php combined files and configuration file config/assets-prod.php generate, but in web/assets directory exists a lot of symlinks (or direct copies if linkAssets === true) of files and folders, which is bundle dependencies themselves. They generate via publish() method of AssetManager. Why Yii don't clean these folders and files after compilation process? Or maybe I do something wrong?

Answer 1

Your script or css files can depend on their sources. For instance you combine css files. One file (from folder "foldername" its important) have following rule
i.sprite-icons {
url(./icons.png)
}
yii concatenate files & move them into "/assests" folder. So Yii also modifies urls. As a result you have following css rule.
i.sprite-icons {
url(./foldername/icons.png)
}
Yii run compressor only after it concatenates files. In your case - gulp.