Node.js Errors

The Node.js applications generally face four types of errors:

• Standard JavaScript errors i.e. <EvalError>, <SyntaxError>, <RangeError>, <ReferenceError>, <TypeError>, <URIError> etc.
• System errors
• User-specified errors
• Assertion errors

Node.js Errors Example 1

Let’s take an example to deploy standard JavaScript error – ReferenceError.

File: error_example1.js

// Throws with a ReferenceError because b is undefined  

try {  

  const a = 1;  

  const c = a + b;  

} catch (err) {  

  console.log(err);  

} 

Open Node.js command prompt and run the following code:

node error_example1.js  

Node.js Errors Example 2

File: timer2.js

const fs = require('fs');  

function nodeStyleCallback(err, data) {  

 if (err) {  

   console.error('There was an error', err);  

   return;  

 }  

 console.log(data);  

}  

fs.readFile('/some/file/that/does-not-exist', nodeStyleCallback);  

fs.readFile('/some/file/that/does-exist', nodeStyleCallback); 

Open Node.js command prompt and run the following code:

node error_example2.js