Providing coding error in nodeJS

Question

I'm just trying to make code on NodeJS, I'm new to NodeJS. I am writing the following block of code.

var fs = require('fs'), os = require('os'); var filename = 'Server.ini'; var serverData = os.hostname() + "\n" + os.platform() + "\n" + os.type() + "\n"; fs.existsSync(filename, function(exists) { if(exists) { console.log("1. " + filename + " file found. Server needs to be updated.") fs.unlinkSync(filename, function(error) { if(error) throw error; console.log("2. " + filename + " is been unlinked from server."); }); } else { console.log("1. " + filename + " not found."); console.log("2. Server needs to be configured."); } }); fs.openSync(filename, "w+", function(error) { if(error) throw error; console.log("3. " + filename + " file is been locked."); }); fs.writeFileSync(filename, serverData, function(error) { if(error) throw error; console.log("4. " + filename + " is now updated."); fs.readFileSync(filename, 'utf-8', function(error, data) { if(error) throw error; console.log("5. Reading " + filename + " file"); console.log("6. " + filename + " contents are below\n"); console.log(data); console.log("-------THE END OF FILE-------"); }); }); 

I edited the code and added synchronization, but now it gave me the following error:

 D:\NodeJS\fs>node eg5.js buffer.js:382 throw new Error('Unknown encoding'); ^ Error: Unknown encoding at Buffer.write (buffer.js:382:13) at new Buffer (buffer.js:261:26) at Object.fs.writeFileSync (fs.js:758:12) at Object.<anonymous> (D:\NodeJS\fs\eg5.js:28:4) at Module._compile (module.js:449:26) at Object.Module._extensions..js (module.js:467:10) at Module.load (module.js:356:32) at Function.Module._load (module.js:312:12) at Module.runMain (module.js:492:10) at process.startup.processNextTick.process._tickCallback (node.js:244:9) D:\NodeJS\fs> 

Something is wrong in my code regarding utf8!

Answer 1

readFileSync does not make a callback. I think you wanted to use readFile instead.

You have the same problem for writeFileSync . These termination callbacks do not make sense when using I / O functions synchronously. It is better to use asynchronous functions (without "Synchronization"), note that they take different arguments.

And the documentation always mentions "utf8" and not "utf-8" , I don’t know if the latter is supported.

Answer 2

According to the node.js API documentation, writeFileSync takes 3 arguments:

• The name of the file to write.
• Data for file input
• An optional object containing parameters, one of which is encoding.

Nowhere is a callback specified. Only the asynchronous version calls back.

http://www.nodejs.org/api/fs.html#fs_fs_writefilesync_filename_data_options

Try this instead of the writeFileSync block:

 fs.writeFileSync(filename, serverData, { encoding: 'utf8'}); console.log("4. " + filename + " is now updated."); var contents = fs.readFileSync(filename, 'utf8'); console.log("5. Reading " + filename + " file"); console.log("6. " + filename + " contents are below\n"); console.log(contents); console.log("-------THE END OF FILE-------");