JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://raw.github.com/ericmbarnard/Knockout-Validation/master/Dist/knockout.validation.js"></script>
<input type="text" data-bind="value: myNumber" />

JavaScript

var MyObjectModel = function(myObject){
    var self = this;
    self.myNumber = ko.observable(myObject.number);
    self.myNumber.extend({
        minLength: {
            params: 7,
            message: "My Number is too short."
        },
        maxLength: {
            params: 7,
            message: "My Number is too long."
        }
    });

    self.errors = ko.validation.group(self);
}

ko.applyBindings(new MyObjectModel({number: 1234657}))