var gulp = require('gulp'),    minifycss = require('gulp-minify-css'),    concat = require('gulp-concat'),    uglify = require('gulp-uglify'),    rename = require('gulp-rename'),    del = require('del');    gulp.task('minifycss', function() {    return gulp.src('css/*.css')  //压缩的文件            .pipe(minifycss())            .pipe(gulp.dest('build/css'))   //输出文件夹           //执行压缩});gulp.task('minifyjs', function() {    return gulp.src('js/*.js')        //.pipe(rename({suffix: '.min'}))   //rename压缩后的文件名        .pipe(uglify())    //压缩        .pipe(gulp.dest('build/js'));  //输出});gulp.task('default', ['minifycss', 'minifyjs','watchcss','watchjs'], function() {});gulp.task('watchcss', function () {    gulp.watch('css/*.css', ['minifycss']);});gulp.task('watchjs', function () {    gulp.watch('js/*.js', ['minifyjs']);});