https://www.renfrewshiregolfunion.co.uk/controls-vue/validations/custom-validation.js?v=1c09ac6248

1var CustomValidation;
2(function (CustomValidation) {
3    var errors = null;
4    function useFormValidation(reactive) {
5        if (!errors) {
6            errors = reactive({});
7        }
8        var isEmpty = function (fieldName, fieldValue) {
9            errors[fieldName] = fieldValue === "" ? "The " + fieldName + " field is required" : "";
10        };
11        var minLength = function (fieldName, fieldValue, min) {
12            errors[fieldName] = fieldValue.length < min ? "The ".concat(fieldName, " field must be atleast ").concat(min, " characters long") : "";
13        };
14        var isEmail = function (fieldName, fieldValue) {
15            var re = /^(([^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
16            errors[fieldName] = !re.test(fieldValue) ? "The ".concat(fieldName, " is not a valid email address") : "";
17        };
18        return { errors: errors, isEmpty: isEmpty, minLength: minLength, isEmail: isEmail };
19    }
20    CustomValidation.useFormValidation = useFormValidation;
21})(CustomValidation || (CustomValidation = {}));