Throwing custom exception types in JavaScript

The number of built-in in JavaScript exceptions is not that large, and they most often cannot satisfy all our needs for different types of exceptions. Therefore, JavaScript has the built-in ability to create exceptions with a custom type.

There are different ways to do this. The simplest one is to pass an object with the keys name and message to throw:

javascripttry {
  throw {name: 'MyError', message: 'an exception text'};
} catch (error) {
  console.log(error.name); // 'MyError'
  console.log(error.message); // 'an exception text'
}

Задание 1

Previously, we made a function that throws an exception when dividing by zero:

javascriptfunction div(a, b) {
  if (b !== 0) {
    return a / b;
  } else {
    throw new Error('division by zero error');
  }
}

Modify this function so that it throws an exception with some kind of type we invented, for example, DivisionByZeroError.

Задание 2

Previously, you made a function that throws an exception when trying to extract the square root of a negative number. Modify your function so that it throws an exception with the type you invented. Think carefully about the name of the exception so that this name is successful.