Regex Tester & Validator

Validates uploaded file names by requiring the base name to start and end with an alphanumeric character, allowing letters, digits, spaces, underscores, and hyphens in between, followed by a dot and a non-empty extension of alphanumeric, underscore, or hyphen characters. This rejects names with leading/trailing spaces, missing extensions, or invalid characters before the dot. The global and multiline flags enable validating multiple file names, one per line.