Thread Summary

The forum discussion revolves around a calculator displaying "undefined" when the last character is deleted. The issue arises from the code's handling of an empty input string. Potential causes include directly evaluating an empty string, not setting a default value for empty input, removing the last character without revalidating, and attempting to display a result for an invalid input. To resolve this, the code should check for an empty input and display a default value (e.g., "0") instead of attempting to evaluate it. Adding error handling and revalidating the input after modifications can also prevent "undefined" from being displayed.