resize images for responsive use

gulpfile.js

// install

// cd node_modules \
// chmod -R a+rwX .

// run without sudo
// npm i del gulp-responsive --unsafe-perm

var del = require('del');
var responsive = require('gulp-responsive');

// Global configuration for all images
var resimgconfig = {
    // Use progressive (interlace) scan for JPEG and PNG output
    progressive: true,
    // Strip all metadata
    withMetadata: false,
    errorOnEnlargement: false,
    withoutEnlargement: true, // copy original file with/without renaming
    skipOnEnlargement: false,
};

// create thumbnails for portfolio
gulp.task('resimg:portfolio', function() {
    // size of portfolio tumb
    var tumbport = 240;
    var sharpfix = 1.3;
    // processing directories
    var dirorig = './app/img/portfolio/'
    var dirtumb = './app/img/tumb/portfolio/'
    // remove tumb sub folders
    del.sync(dirtumb);
    // create tumbs
    return gulp.src(dirorig + '**/*.*')
        .pipe(responsive({
            '**': [{
                // convert png to jpg
                flatten: true, // add backgoround #fff need instal npm i color
                rename: {
                    extname: '.jpg' // rename ext and converting (converting format get from extname)
                },
                // end converting
                width: tumbport,
                height: tumbport,
                quality: 90,
                //min: true, // min size will be tumbport ()
                max: true // max size will be tumbport
            }, {
                width: tumbport / 2,
                quality: 60,
                blur: true,
                rename: {
                    suffix: '-placeholder'
                },
            }],
        }, resimgconfig))
        .pipe(gulp.dest(dirtumb));
});