TypeError：无法读取Node.js中未定义的属性“ length”

Question

I'm trying to create a server but it is throwing me an error in console

$ node server1185
Server listening at 1185

C:\Users\Bharat\Desktop\Nodejs\server1185.js:9

res.writeHead(200,{'Content-Type':'text/html', 'Content-Length': data.length
                                                                  ^

TypeError: Cannot read property 'length' of undefined
    at ReadFileContext.callback (C:\Users\Bharat\Desktop\Nodejs\server1185.js:9:
71)
    at FSReqWrap.readFileAfterOpen [as oncomplete] (fs.js:420:13)

My Node.js code is following

 var http = require('http'); var fs = require('fs'); var server = http.createServer(function(req, res){ displayForm(res); }); function displayForm(res){ fs.readFile('form.html', function(err,data){ res.writeHead(200,{'Content-Type':'text/html', 'Content-Length': data.length }); res.write(data); res.end(); }); } server.listen(1185); console.log('Server listening at 1185'); 

It is throwing an error in data.length, an explanation will be appreciated.

Answer 1

You have to handle the err object properly Log both err and data object. You will understand the problem

 if(err)
    {
        console.log(err)
    }
    else
  {
   res.writeHead(200,{'Content-Type':'text/html', 'Content-Length': data.length
 }