How to Throw an Error in JavaScript?

A necessary part of strong programming advancement is the means by which to handle errors. Throwing errors is a way to handle and respond to unexpected conditions in your JavaScript code. Coders who know how to throw errors can foster code that is simpler to use and keep up with.

Why Throw Errors?

Throwing errors enables you to do the following:

• You can stop your code's standard execution and let others know that something startling occurred by raising an error.
• An error message that makes sense of what turned out badly or code gone wrong can be incorporated when an error is thrown.
• You might guarantee that your application can come up short or work effortlessly by utilizing try...catch blocks to catch the thrown errors and treat them.

The Statement for Throwing Error: throw

To throw an error in JavaScript, utilize the throw statement. The syntax is very basic:

Throwing a Basic Error

Here is a basic representation of a basic error:

In this example, an Error object case is produced, thrown, and has the message "Something went wrong!"

Utilizing Custom Error Types

Albeit the most successive error type to throw in JavaScript is an Error object, there are various other underlying error types that may be useful for more specific error handling:

• Type Error
• Syntax Error
• Reference Error
• Range Error
• URI Error

For example:

By extending the Error class, you may furthermore make interesting error types:

Conditionally Throwing Errors

In a few of the cases, error messages are normally thrown under particular conditions. As a simple example, see the below example:

Code

Output:

 2 Cannot divide by zero! 

For this situation, trying to isolate by zero makes the divide function return an error. The issue is recognized by the try...catch block, which then logs the error message to the control centre.

Error Propagation

Up the call stack, errors could spread until an error handler catches them. As an outline, think about this:

Code

Output:

 Error in functionB 

An error thrown in function B in this example goes to function A and is caught by the try...catch block there.

Try, catch, finally keywords

The final block can be skipped; it runs whether an error was raised. It's useful for getting out assets or completing assignments that need to be finished whether an error happened.

Code

Output:

 Something went wrong This will always run 

Example:

Let's see an example code to see various types of errors and handling them.

Code

Output:

 Throwing generic error: Caught a generic error: Error - This is a generic error! Execution in finally block. Throwing type error: Caught a type error: TypeError - This is a type error! Execution in finally block. Throwing range error: Caught a range error: RangeError - This is a range error! Execution in finally block. Throwing custom error: Caught a custom error: CustomError - This is a custom error! Execution in finally block. Throwing none error: No error thrown. Execution in finally block. 

Conclusion

In JavaScript, throwing errors is an area of strength to manage exceptional cases and ensure your code is steady and sensible. You might fabricate more trustworthy JavaScript code by figuring out how to utilize the throw order, custom error types, and try...catch blocks. To give further setting to the issues that emerge in your application, remember to constantly incorporate significant error messages and contemplate creating novel error types.