Conditional fields

«Conditional fields» is a JavaScript library that allows you to show or hide form fields based on user selections.

This gives you the opportunity to flexibly customize your HTML forms and to request only needed information from users.

Advantages

• compatibility with any CMS
• simple integration
• easy to use
• pure JavaScript without external dependencies
• 2.4 KB gzipped size

Install

npm i conditional-fields

Setup

You can choose between:

1. Classic web

<script src="conditional-fields.browser.js"></script>

2. ES6 Modules

import ConditionalFields from 'conditional-fields';

Usage

First of all, you will need an HTML form.

To enable conditional logic you should add data-rules attribute to the conditional field.

<form action="#" method="POST">
    <div class="row">
        <input type="checkbox" name="is_adult"> Are you an adult?
    </div>
    
    <div class="row">
        <input name="phone" data-rules='[{"name": "is_adult", "value": ["true"]}]'>
    </div>
    
    <button type="submit">Submit</button>
</form>

new ConditionalForm(document.querySelector('form'));

In the example above input with name phone will be visible only if input with name is_adult has value that equals to true.

You can also add several values:

<form action="#" method="POST">
    <div class="row">
        <input type="text" name="strange_thing" placeholder="Type something">
    </div>
    
    <div class="row">
        <input name="alert" data-rules='[{"name": "strange_thing", "value": ["floppy", "disk", "floppy disk"]}]'>
    </div>
    
    <button type="submit">Submit</button>
</form>

In the example above input with name alert will be visible only if input with name strange_thing has the value that equals to floppy or disk or floppy disk.

Or even several rules:

<form action="#" method="POST">
    <div class="row">
        <input type="checkbox" name="is_adult"> Are you an adult?
    </div>
    
    <div class="row">
        <input type="checkbox" name="is_agreed"> Do you agree with the terms?
    </div>
    
    <div class="row">
        <input name="phone" data-rules='[{"name": "is_adult", "value": ["true"]}, {"name": "is_agreed", "value": ["true"]}]'>
    </div>
    
    <button type="submit">Submit</button>
</form>

In the example above input with name phone will be visible only if input with name is_adult has value that equals to true and input with name is_agreed has value that equals to true.

You can also provide your own functions to show and hide form fields:

new ConditionalForm(document.querySelector('form'), {
    onShow: (root) => root.closest('div.row').style.display = 'block',
    onHide: (root) => root.closest('div.row').style.display = 'none'
});

Where root it is a conditional field HTML node.

Restrictions

Right now this library allows using only default form fields but in the future, there will be an option where you can define your own custom elements and make conditional not only form elements but any type of HTML element.