Errors Javascript

• We can throw errors using throw statement.
• Used to generate custom errors
• You can throw any type of object, but it's common to throw Error objects for clarity & standardization.
• Try Catch Javascript
• In case of async functions you can also return Promise.reject() with anything as parameter for the error case.

Syntax

throw expression;

Example 1: Throwing a custom error

function divide(a, b) {
	if (b === 0) {
		throw new Error("Division by zero is not allowed");
	}
	return a/b;
}

try {
	divide(4, 0);
} catch(error) {
	console.error(error.message); // Output: Division by zero is not allowed
}

Example 2: Throwing custom objects

function login(username) {
	if (!username) {
		throw { message: "Username is required", code 400};
	}
	return "Logged in!";
}

try {
	login("");
} catch (error) {
	console.error(error.message); // Output: Username is required
}