A validation error is thrown when the command is wrongly used by the user. For example: If the user passes some invalid options or arguments to the command.

Available build-in argument types.

Boolean type handler. Excepts true, false, 1, 0

Number type handler. Excepts any numeric value.

String type handler. Excepts any value.

Parse command line arguments.

Flags post validation. Validations that are not already done by the parser.

Flag argument definition.

Flag options.

Result of the parseFlags method.

Parser options.

Type details.

Default flag value

Value handler for custom value processing.

Custom type handler/parser.