The Meaning of Undefined

What is Undefined?

In computing, undefined is a special value that is used to indicate that a variable or expression has not been assigned a value. It is different from null, which is a value that is explicitly assigned to a variable to indicate that it does not have a value.

Undefined values can occur for a number of reasons. For example, a variable may be declared but never assigned a value. Or, an expression may involve an operation that is not defined for the given operands.

How to Handle Undefined Values

When you encounter an undefined value, it is important to handle it gracefully. This means that you should not allow the undefined value to cause an error or crash. Instead, you should take steps to handle the undefined value in a way that is appropriate for your application.

There are a number of ways to handle undefined values. One common approach is to use a default value. For example, you could assign a variable to the empty string if it has not been assigned a value. Another approach is to check for undefined values before using them. For example, you could use the `isUndefined()` function to check if a variable is undefined before using it in an operation.

Conclusion

Undefined values are a common occurrence in computing. It is important to understand what undefined values are and how to handle them gracefully. By following the tips in this article, you can avoid errors and crashes caused by undefined values.