demo

js
const woa=require('./woa');
let fs=require('fs')

let app=new woa();

app.use(async (ctx,next)=>{

  let p=new Promise((resolve)=>{
    setTimeout(()=>{
      resolve();
    },2000)
  });
  await p.then(()=>{
    console.log(1);
  })

  next();
  console.log('end',1);
})

app.use((ctx,next)=>{
  console.log(2);
  console.log('end',2);
})

app.use((ctx,next)=>{
  console.log(3);

})

app.listen(9092,()=>{
  console.log('http://localhost:9092')
});

实现woa

js
const http=require('http');

let context= {
  get url(){
    return this.req.url
  },
  set url(val){
    this.req.url=val;
  },
  get body(){
    return this.res.body;
  },
  set body(val){
    this.res.body=val;
  }
};


class Application {
  constructor(){
    this.callbacks=[]
  }
  use(callback){
   this.callbacks.push(callback||function(){});
  }
  middleware(ctx,index){
    if(index==null)index=-1;
    index++;
    let callback=this.callbacks[index];
    if(!callback)return;
    callback(ctx,()=>{
      this.middleware(ctx,index);
    })
  }
  listen(...args){
    const server=http.createServer(async (req,res)=>{
      let ctx=this.createCtx(req,res);
      if(this.callbacks.length>0){
        this.middleware(ctx);
      }
     // await this.callback(ctx);
      res.end(ctx.body)
    });
    server.listen(...args);
  }
  createCtx(req,res){
     let ctx=Object.create(context);
     ctx.req=req;
     ctx.res=res;
     ctx.res.body='';
     return ctx;
  }

}

module.exports=Application;