gulpfile.js

const gulp = require('gulp');
const entry = './src/server/**/*.js';
const babel = require('gulp-babel');
const watch = require('gulp-watch');
const cleanEntry = ['./src/server/config/index.js']; 
const rollup = require('gulp-rollup'); // 做流清洗 也就是tree shaking
const replace = require('rollup-plugin-replace'); // 用提供的结果去替换打包后的变量名

function builddev() {
    return watch(entry, { ignoreInitial: false }, function () {
        gulp.src(entry)
        .pipe(babel({
            babelrc: false, // 需要自己独立的编译 很重要 忽略外面的.babelrc文件
            "plugins": ["@babel/plugin-transform-modules-commonjs"] // 需要安装@babel/plugin-transform-modules-commonjs
        })).pipe(gulp.dest('dist'));
    })
}

// 上线环境
function buildprod() {
    return gulp.src(entry)
    .pipe(babel({
        babelrc: false, 
        ignore: cleanEntry, // 忽略掉此文件
        "plugins": ["@babel/plugin-transform-modules-commonjs"] 
    })).pipe(gulp.dest('dist'));
}

// 上线配置 tree shaking
function buildconfig() {
    return  gulp.src(entry)
    // transform the files here.
    .pipe(rollup({
        output: {
            format: "cjs" // common js 规范
        },
        // any option supported by Rollup can be set here.
        input: cleanEntry,
        plugins: [
            replace({
              'process.env.NODE_ENV': JSON.stringify('production')
            })
          ]
    }))
    .pipe(gulp.dest('./dist'));
}

// 校验
function lint() {}

// Gulp 4抛弃了依赖参数（dependency parameter），用执行函数来代替：
// gulp.series 用于串行（顺序）执行
// gulp.parallel 用于并行执行

let build = gulp.series(builddev);

if (process.env.NODE_ENV == "production") {
    build = gulp.series(buildprod, buildconfig);
}

if (process.env.NODE_ENV == "lint") {
    build = gulp.series('lint');
}


gulp.task('default', build);