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Kavie is a small and easy to use knockout js validation library.


You can download kavie from npm

npm install kavie

Then include it in your project after knockout js

<script src="/path/to/knockout.js"></script>
<script src="/node_modules/kavie/dist/kavie.js"></script>


function ViewModel(){
  var self = this;
  self.value = ko.observable().extend({
    kavie: {
      required: true
  self.submit = function(){
    if (Kavie.isValid(self)){
      console.log("All Good!");

Html Side

Kavie works by adding a hasError variable to the observable. This gives the flexibility to add color changing to any element you want

<input type="text" data-bind="textInput: value, css:{'error': value.hasError}"/>
<span data-bind="visible: value.hasError">Uh Oh! There was an error!</span>

Validation Messages

You can use a validation message to display to the user if the validation failed

<input data-bind="textInput: value">
<div data-bind="text: value.errorMessage"></div>

These validation messages are stored on the validators see custom rules for more information

Validation rules

There are a few validation rules build in

self.value = ko.observable().extend({
    kavie: {
      required: true, // [boolean] this one is obvious 
      maxLength: 3, // [int] max amount of characters: 3 
      minLength: 2, // [int] min amount of characters: 2 
      date: true, // [boolean] validates dates based on js dates 
      birthdate: true, // [boolean] uses date, and must be in past with persons age less than 120 
      phone: true, // [boolean] uses regex to validate a valid 10 digit phone number 
      email: true, // [boolean] uses regex to validate a valid email 
      numeric: true, // [boolean] must be an integer 
      regexPattern: /([A-Z])\w+/ // [regex] matches a pattern 

It is important to note that on the date, birthdate, phone, email, and numeric validators, if the users input is null, undefined, or empty they will return true. This is so you can still have optional values and use these validators. If you want them required, add the required validator.

More Features

There is much more to kavie, but in order to keep the readme simple the advanced features have been moved to the wiki


Thanks of taking a look at kavie. If you have any problems let me know and I would love to help you out