最近在折腾的时候又想写less了，但是换框架了，成了thinkjs,考虑到开发阶段一直编译编译less的情况..最终根据middleware的特点实现了一个超级简单的less中间件。

作用很简单，我想实现的目标也很简单，在html中正常写css链接，当时请求会被less中间件拦截，然后根据路径查找less文件，并进行编译，最终写入到目标css文件中。

这个只在开发模式下使用，生产环境不需要使用。主要就是方便使用less编写样式。 https://cdn.pixabay.com/photo/2019/12/04/23/34/sheep-4673941__340.jpg

think-less

A less middleware for thinkjs 3.0 on development enviroment. Compiler less file to css when request xxx.css file in pages.

Installation

npm install think-less --save-dev

API

Modify /src/config/middleware.js .The less middleware should before resource middleware.

const less = require('think-less');
const path = require('path');
const isDev = think.env === 'development';

module.exports = [
    {
        handle: less,
        enable: isDev ? true : false,
        options: {
            root: path.join(think.ROOT_PATH, 'res'),
            target: path.join(think.ROOT_PATH, 'www'),
            lessOptions: {
                paths: [path.join(think.ROOT_PATH, 'res')],
                compress: true
            }
        }
    }
]

Options

• root : Root directory to find less file .
• target : Root directory to place css file .
• lessOptions : Options of Less.js

源码

代码也很简单，直接使用的less的模块进行编译，如下：

//thinkjs middleware of less compiler
const less = require('less');
const path = require('path');
const fs = require('fs');
const mkdirsp = require('mkdirsp');

module.exports = (options,app)=>{
    return async (ctx,next)=>{
        let extname = path.extname(ctx.path);
        if(extname.toLowerCase() != '.css'){
            return next();
        }
        let filePath = path.join(options.root,ctx.path.substr(0,ctx.path.indexOf('.css'))+'.less');
        let targetPath = path.join(options.target,ctx.path);
        if(!fs.existsSync(filePath)){
            return next();
        }
        let content = Buffer.from(fs.readFileSync(filePath)).toString('utf8');
        try{
            await mkdirsp(path.dirname(targetPath));
            let out = await less.render(content,options.lessOptions)
            fs.writeFileSync(targetPath,out.css);
        }catch(e){
            return Promise.reject(e);
        }
        return next();
    }
}