Gulp构建过程核心工作原理

const fs = require('fs')
const { Transform } = require('stream')  

exports.default = () => {
    //文件读取流
    const read = fs.createReadStream('normalize.css')
    //文件写入流
    const write = fs.createWriteStream('normalize.min.css')
    //文件转换流
    const transform = new Transform({
        transform: (chunk, encoding, callback) => {
            //核心转换过程实现
            const input = chunk.toString()
            const output = input.replace(/\s+/g, '').replace(/\/\*.+?\*\//g,'')
            callback(null, output) //失败回调 第一个参数是失败的对象
        }
    })
    
    //把读取出来的文件流导入写入文件流

    read
    .pipe(transform)  //转换
    .pipe(write)      //写入
    return read
}