Read file in Node.js

 var fs = require('fs');  
 var path = require('path');  
 exports.testDir = path.dirname(__filename);  
 exports.fixturesDir = path.join(exports.testDir, 'fixtures');  
 exports.libDir = path.join(exports.testDir, '../lib');  
 exports.tmpDir = path.join(exports.testDir, 'tmp');  
 exports.PORT = +process.env.NODE_COMMON_PORT || 12346;  
 // Read File  
 fs.readFile(exports.tmpDir+'/world.csv', 'utf-8', function(err, content) {  
  if (err) {  
   got_error = true;  
  } else {  
   console.log('cat returned some content: ' + content);  
   console.log('this shouldn't happen as the file doesn't exist...');  
   //assert.equal(true, false);  
  }  
 });  

The readFile is passed two arguments (err, data), where data is the contents of the file.