//文件结构

gulpfile.js

var gulp = require('gulp');

var sass = require('gulp-sass'); //编译scss

var cleanCSS = require('gulp-clean-css');//压缩css

var gulpautoprefixer = require('gulp-autoprefixer');//自动添加前缀

var uglify = require('gulp-uglify'); //js 压缩

var gulpImagemin = require('gulp-imagemin'); //图片压缩

var browserSync = require('browser-sync').create(); //浏览器自动重载

var reload = browserSync.reload;

sass.compiler = require('node-sass');

gulp.task('scss',(cb)=>{

gulp.src('static/**/*.scss')

.pipe(sass().on('error', sass.logError))

.pipe(gulpautoprefixer())

.pipe(cleanCSS())

.pipe(gulp.dest('public'))

.pipe(reload({stream: true}))

cb();

})

gulp.task('uglifyJs', cb=>{

gulp.src('static/**/*.js')

.pipe(uglify())

.pipe(gulp.dest('public'))

cb();

})

gulp.task('imagemin', cb=>{

gulp.src('static/img/*')

.pipe(gulpImagemin())

.pipe(gulp.dest('public/img'))

cb();

})

//gulp 文件监听

gulp.task('watch',cb=>{

browserSync.init({

proxy: "http://localhost:8081",

files: ["public/**/*.*", "views/**", "static/**"],

notify: false

});

gulp.watch('static/**/*.scss', gulp.series('scss'))

gulp.watch('static/**/*.js', gulp.series('uglifyJs'))

gulp.watch('static/img/*', gulp.series('imagemin'))

gulp.watch("views/*.html").on('change', reload);

cb();

})

//依次执行任务 顺序为 scss 》 uglifyJs 》 imagemin 》 watch 》 default

gulp.task('default',gulp.series('watch',gulp.series( 'scss', 'uglifyJs', 'imagemin')), cb=>{

cb();

})

 具体使用方法参考官方文档

ps: 中文版的是gulp3.0的文档api不完整