When should I use undefined in JavaScript?

When should I use undefined in JavaScript?

In JavaScript, 'undefined' is a primitive value that indicates a variable has been declared but not assigned a value. You can use it when you want to check if a variable has been initialized.

Can you give me an example of when it's appropriate to use undefined?

Sure! If you have a function that takes an optional parameter, you can check if that parameter is undefined to determine if it was provided.

What happens if I try to access a property of an undefined variable?

If you try to access a property of an undefined variable, it will throw a TypeError. It's important to check if the variable is defined before accessing its properties.

Are there any best practices for using undefined?

Yes, it's best to avoid explicitly assigning undefined to variables. Instead, let JavaScript handle it automatically when a variable is declared but not initialized.