error handling in asynchronous node.js calls

Question

I\'m new to node.js although I\'m pretty familiar with JavaScript in general. My question is regarding \"best practices\" on how to handle errors in node.js.

Normall

Answer 1

At the time of this writing, the approach I am seeing is to use "Promises".

http://howtonode.org/promises
https://www.promisejs.org/

These allow code and callbacks to be structured well for error management and also makes it more readable. It primarily uses the .then() function.

someFunction().then(success_callback_func, failed_callback_func);

Here's a basic example:

  var SomeModule = require('someModule');

  var success = function (ret) {
      console.log('>>>>>>>> Success!');
  }

  var failed = function (err) {
    if (err instanceof SomeModule.errorName) {
      // Note: I've often seen the error definitions in SomeModule.errors.ErrorName
      console.log("FOUND SPECIFIC ERROR");
    }
    console.log('>>>>>>>> FAILED!');
  }

  someFunction().then(success, failed);
  console.log("This line with appear instantly, since the last function was asynchronous.");