Catching errors thrown inside Nodejs promise

catching-promise-errors.js

'use strict';


var Promise = require('promise');


/** @desc A function that returns a promise with an error-prone code. */
function build() {
  return new Promise(function(fulfill, reject) {
    
    // This line is going to throw an error forcing JavaScript
    // interpreter to stop, and promise fulfillment on the
    // next line is not going to be reached.
    whatever.error = 'error';
    
    fulfill();
  });
}


build().then(function(result) {
  // This is line is not going to be reached, because promise catched
  // an error before fulfillment.
  console.log(result);

}, function(error) {
  // When program throws an error inside a promise, program does
  // not exit (like it would without a promise or without try/catch), 
  // but it rejects the promise automatically, executing `reject`
  // callback with an Error as the only argument.
  console.error(error);
});