Validate if a string is Base64-encoded.
Valid values:
validator.base64().validate('YW55IGNhcm5hbCBwbGVhc3VyZS4=');
validator.base64().validate('YW55IGNhcm5hbCBwbGVhc3VyZQ==');
validator.base64().validate('YW55IGNhcm5hbCBwbGVhc3Vy');
validator.base64().validate('YW55IGNhcm5hbCBwbGVhc3U=');
validator.base64().validate('YW55IGNhcm5hbCBwbGVhcw==');Invalid values:
validator.base64().validate(null);
validator.base64().validate(undefined);
validator.base64().validate('');
validator.base64().validate('hello!');
validator.base64().validate('=c3VyZS4');
validator.base64().validate('YW55IGNhcm5hbCBwbGVhc3VyZ===');