gulpfile.js

var gulp = require("gulp"),
    del = require("del"),
    stylus = require("gulp-stylus"),
    prefix = require("gulp-autoprefixer"),
    rename = require("gulp-rename"),
    uglify = require("gulp-uglify"),
    imagemin = require("gulp-imagemin");

function clean(cb){
  const deletedPaths = del.sync(["source/dist/*"]);
  cb();
}

function cssMinify(){
  gulp.src("source/css/main.styl")
    .pipe(rename({
      suffix: ".min"
    }))
    .pipe(stylus({
      compress: true
    }))
    .pipe(gulp.dest("source/dist/css"));
}

function cssPrefix(){
  gulp.src("source/dist/css/main.min.css")
    .pipe(prefix())
    .pipe(gulp.dest("source/dist/css"));
}

function jsMinify(){
  gulp.src("source/js/*.js")
    .pipe(rename({
      suffix: ".min"
    }))
    .pipe(uglify())
    .pipe(gulp.dest("source/dist/js"));
}

function imageMinify(){
  gulp.src("source/images/*.jpeg*")
    .pipe(rename({
      suffix: ".min"
    }))
    .pipe(imagemin([
      imagemin.mozjpeg({quality:70, progressive: true})
    ]))
    .pipe(gulp.dest("source/dist/images"));
  gulp.src("source/images/*.svg").pipe(gulp.dest("source/dist/images"));
}

function buildAll(cb){
  cssMinify();
  jsMinify();
  imageMinify();
  cb();
}
function minImg(cb){
  imageMinify();
  cb();
}
function minCss(cb){
  cssMinify();
  cb();
}
function minJs(cb){
  jsMinify();
  cb();
}
function prefixCss(cb){
  cssPrefix();
  cb();
}
exports.default = buildAll;
exports.clean = clean;
exports.img = minImg;
exports.css = minCss;
exports.fix = prefixCss;
exports.js = minJs;