nodejs learning articles (2) - read the image routing method

Usually we develop projects should be used when the picture, then the picture nodejs how to read it?
We look at, because the number of pages in a picture is uncertain, but we can not write each image to its src path, this time the best way is to write a special read picture route by route load picture, so quick and easy our understanding.
File Directory:

I want to load images in index page

Note: Question mark? Represents the front part of the route, the path is a question mark behind the picture (relative to the server file), I was first_server.js file
1, in their definition of the new directory server files
I was:
first_server.js

var http=require('http');
var url=require('url');
var router=require('./module/router');
http.createServer(function (request,response) {
    response.writeHead(200, {'Content-Type': 'text/html;charset=utf-8'});
    if (request.url!=='/favicon.ico'){//清除二次访问
        var path=url.parse(request.url).pathname;//获取当前路径
        if(path==='/')path='/index';
        path=path.substr(1);//获取去掉根符号‘/’的当前路径
        router[path](request,response);//路由，path是一个变量，如login、register、index
    }
}).listen(5200);//端口号为5200

Explanation : The value is not the same path twice,

if (path === '/') action path = '/ index' if the time of the visit is not input path, to enter the index page

Note : router [path] must be defined through the routing module inside job, otherwise there will not be found error

2, write routing module (router.js)

var url = require('url');
var optfile=require('./optfile');//导入自定义模块要加路径'./'
module.exports={
    readImg:function(req,res){
        optfile.readImg(req,res);
    },
    index:function(req,res){
        optfile.index('./file/index.html',res);
    }
}

3, the preparation of operating documents (optfile.js)

var fs = require('fs');
function recall(res,data,ext){
    if (!ext)ext='html';//默认输出格式为HTML
    res.writeHead(200, {'Content-Type': 'text/'+ext+';charset=utf-8'});
    res.end(data);//向浏览器输出取得的数据
}
module.exports={
    readImg:function (req,res) {
        var path=req.url.split('?')[1];
        var data = fs.readFile(path,'binary',function (err,data) {
            if (!err){
                res.writeHead(200, {'Content-Type': 'image/jpeg'});//输出类型
                res.write(data,'binary');//二进制方式
            }else {
                res.end('err');
            }
        })
    },
    index:function (path,res) {
        var data = fs.readFile(path,function (err,data) {
            if (!err){
                data=data.toString();
                recall(res,data);
            }else {
                res.end('err');
            }
        })
    }
};

Because the picture is transmitted in binary form in nodejs, so the output file to add 'binnary' represent a binary output.
Req.url equivalent request.url represents achievement of the path of the current request, here to represent all the image path,
req.url .split ( '?') represents the path will be made of string? Split into an array,
req.url.split ( '?') [. 1] represented by taking a string? No later parts, namely the relative path pictures
do not understand can see below, I console it:

operation result:

Reproduced in: https: //www.jianshu.com/p/cfeb8c082651