节点js服务器`${req.method} ${req.url}`

Question

I nicked this code from somewhere a while ago with the idea of coming back to understand it some more. iv been running it on a pi for a while now with no issues but I needed to restore a backup of the os from before when I had the web server running and since doing so I haven't been able to get it running I keep getting a syntax error (below) if I run the same code on another pc it works fine. any idea where I can look im all out of idea?

also, I don't know what the $ means is it jquery?

ERROR

 etc/server/app.js:10
  console.log(`${req.method} ${req.url}`);
              ^
SyntaxError: Unexpected token ILLEGAL
    at Module._compile (module.js:439:25)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:906:3

NICKED CODE

var http = require('http').createServer(handler); //require http server, and create server with function handler()
const path = require('path');
const url = require('url');
var fs = require('fs'); //require filesystem module

var io = require('socket.io')(http) //require socket.io module and pass the http object (server)

http.listen(3000); //listen to port 8080
function handler (req, res) { //create server
  console.log(`${req.method} ${req.url}`);

  const parsedUrl = url.parse(req.url);
  // extract URL path
  let pathname = `.${parsedUrl.pathname}`;
  // maps file extention to MIME types
  const mimeType = {
    '.ico': 'image/x-icon',
    '.html': 'text/html',
    '.js': 'text/javascript',
    '.json': 'application/json',
    '.css': 'text/css',
    '.png': 'image/png',
    '.jpg': 'image/jpeg',
    '.wav': 'audio/wav',
    '.mp3': 'audio/mpeg',
    '.svg': 'image/svg+xml',
    '.pdf': 'application/pdf',
    '.doc': 'application/msword',
    '.eot': 'appliaction/vnd.ms-fontobject',
    '.ttf': 'aplication/font-sfnt'
  };

  fs.exists(pathname, function (exist){
      if(!exist){
        //file not found, return 404
        res.writeHead(404, {'Content-Type': 'text/html'});
        return res.end("404 Not Found");
      }

      //if directory, return index.html
      if(fs.statSync(pathname).isDirectory()){
          pathname += '/index.html';
      }

      //read file
      fs.readFile(pathname, function(err, data){
          if(err){
            res.writeHead(500, {'Content-Type': 'text/html'});
            return res.end("500 Error getting file.");
          }else{
              const ext = path.parse(pathname).ext;
              res.setHeader('Content-type', mimeType[ext] || 'text/plane');
              res.end(data);
            }
        })
  });
}

Answer 1

This is a ES6+ Template Literal: ${req.method} ${req.url} .

Also known in other languages as "string interpolation". It has nothing to do with jQuery. See more on it here .

In this case it is just printing the request method and the request URL to the console . Something like: "GET http://localhost:3000/posts" . You can think of it as logging requests in the command line.

What has mostly likely gone wrong is you are using an older version of Node that does not support it. run the following in your terminal:

node -v

is the result 0.12.18 or less? if so that's too old.

the following solutions exist:

• You can upgrade your version of node

• You can just remove the line entirely since it only prints out to the console and has no actual effect programmatically (unless you actually need to see what it's printing).

• You can also change it to the older concatenated style of string joining like so:

  console.log(req.method + ' ' + req.url)

Personally I'd recommend upgrading your version of node to the latest LTS version.

Answer 2

console.log(`${req.method} ${req.url}`);

This is a new way of creating strings in JavaScript. The piece of code is trying to log something to the terminal: a string with two JavaScript variables and a space in between them. It can probably be safely removed, and everything will function the same.