@modular-forms/react/dist/source/validation/mimeType.js

The modular and type-safe form library for React

/**
 * Creates a validation functions that validates the file type.
 *
 * @param requirement The MIME types.
 * @param error The error message.
 *
 * @returns A validation function.
 */
export function mimeType(requirement, error) {
    const mimeTypes = Array.isArray(requirement) ? requirement : [requirement];
    return (value) => value &&
        (Array.isArray(value)
            ? [...value].some((file) => !mimeTypes.includes(file.type))
            : !mimeTypes.includes(value.type))
        ? error
        : '';
}