Localization

FormValidation.formValidation(
    document.getElementById('loginForm'),
    {
        fields: {
            username: {
                validators: {
                    notEmpty: {
                        message: 'The username is required'
                    },
                    stringLength: {
                        message: 'The username must be more than 6 and less than 30 characters long',
                        ...
                    },
                    regexp: {
                        message: 'The username can only consist of alphabetical, number and underscore',
                        ...
                    },
                }
            },
            password: {
                validators: {
                    notEmpty: {
                        message: 'The password is required'
                    },
                    stringLength: {
                        message: 'The password must have at least 8 characters',
                        ...
                    },
                }
            },
        },
        plugins: {
            ...
        }
    }
);

<script src="/vendors/formvalidation/dist/js/FormValidation.min.js"></script>
<!-- The language package has to be loaded after FormValidation(.min).js -->
<script src="/vendors/formvalidation/dist/js/locales/en_US.min.js"></script>

<script>
    document.addEventListener('DOMContentLoaded', function(e) {
        const fv = FormValidation.formValidation(
            document.getElementById('demoForm'),
            {
                // Set the default locale
                locale: 'en_US',
                localization: FormValidation.locales.en_US,

                // Ignore the message option
                // It will be taken from the language package
                fields: {
                    username: {
                        validators: {
                            notEmpty: {
                            },
                            stringLength: {
                                min: 6,
                                max: 30,
                            },
                            regexp: {
                                regexp: /^[a-zA-Z0-9]+$/
                            },
                        }
                    },
                    password: {
                        validators: {
                            notEmpty: {
                            },
                            stringLength: {
                                min: 8
                            },
                        }
                    },
                },
                plugins: {
                    ...
                },
            }
        );
    });
</script>