Custom error type in JavaScript

error.js

function MyError(message) {
  this.name = 'MyError';
  this.message = message;
  this.stack = (new Error()).stack;
}

MyError.prototype = new Error();
MyError.prototype.constructor = MyError;

try {
  throw new MyError("custom message");
} catch (e) {
  if (e instanceof MyError) {
    console.log(e.name);     // "MyError"
    console.log(e.message);  // "custom message"
  }
}