horprogs/Just-validate - Githubissues

Modern, simple, lightweight (~5kb gzip) form validation library written in Typescript, with no dependencies (no JQuery!). Support a wide range of predefined rules, async, files, dates validation, custom error messages and styles, localization. Supporting writing custom rules and plugins.

Why JustValidate?

It's a right choice for you, if you have a site, a landing page without React, JQuery etc. and you want to quick, simple and powerful solution for validating your form.

Features

small size and zero dependencies
no need to change your HTML
a wide range of pre-defined rules
custom rules
support plugins
custom styles and css classes for invalid fields and error messages
custom messages
showing tooltips as error messages
custom places for the error labels
localization (defining error messages for different languages)
user-friendly setup: console warning messages if something incorrect
written in Typescript and good test coverage

Installation

npm

npm install just-validate --save

yarn

yarn add just-validate

And then use it as an imported module:

import JustValidate from 'just-validate';

const validate = new JustValidate('#form');

Or if you don't use module bundlers, just include JustValidate script on your page from CDN and call it as window.JustValidate:

<script src="https://unpkg.com/just-validate@latest/dist/just-validate.production.min.js"></script>
<body>
  <script>
    const validate = new window.JustValidate('#form');
  </script>
</body>

Predefined rules

There are plenty of rules which you could use out of the box:

required, non-empty fields
valid email address
min/max text length
valid number
min/max number
valid password
valid strong password
check for the custom regexp
min/max count of uploaded files
min/max size, types, extensions, names of uploaded files
format date, check for isAfter/isBefore dates

Quick start

Let's say we have a basic HTML layout:

<form action="#" id="form" autocomplete="off">
  <label for="name">Enter your name</label>
  <input
    type="text"
    class="form__input form-control"
    placeholder="Enter your name"
    autocomplete="off"
    name="name"
    id="name"
  />
  <label for="email">Enter your email</label>
  <input
    type="email"
    class="form__input form-control"
    placeholder="Enter your email"
    autocomplete="off"
    name="email"
    id="email"
  />
  <button class="btn btn-primary" id="submit-btn">Submit</button>
</form>

Next, let's add JustValidate to our layout and define some simple rules.

First, we should create the instance new JustValidate('#form') by passing a form selector, or the element as an argument.

Second, we call .addField() with a field selector as the first argument and an array of rules as the second argument.

const validation = new JustValidate('#form');

validation
  .addField('#name', [
    {
      rule: 'minLength',
      value: 3,
    },
    {
      rule: 'maxLength',
      value: 30,
    },
  ])
  .addField('#email', [
    {
      rule: 'required',
      errorMessage: 'Email is required',
    },
    {
      rule: 'email',
      errorMessage: 'Email is invalid!',
    },
  ]);

And that's it! Now our form is validated!

Please, check out the examples and documentation. Or try the playground.