form-js

FormJS

This library provides a simple API to manipulate a form or its related elements with JavaScript. Supports IE10+, all modern browsers, and mobile.

It's important for you to use native form elements (i.e. <select>, <input>, etc) because they come with critical built-in logic needed for the interactions that users expect. Like tabbing to fields, pressing enter or spacebar to commit a dropdown item, mobile keyboard input triggering, etc.

Benefits

• Automatic form data binding (JSON data and JS object literals)
• Use CSS to easily customize hard-to-style native elements (i.e. dropdowns)
• Listen to user events on forms
• Easily change and update form elements and their values with JavaScript
• Trigger events programmatically

Support

• Checkboxes
• Radio Buttons
• Input Fields
• Dropdowns (Select Elements)
• Text Areas
• Entire forms

Usage

You can quickly start using the Form class as a standalone package, by using one of the pre-built javascript files. Alternatively, you can also use the source files directly if you are running your own build processes.

Styling form elements

Let's say you wanted to style a dropdown menu with the following html:

<select>
    <option value="MD">Maryland</option>
    <option value="VA" selected>Virginia</option>
    <option value="DC">Washington, DC</option>
</select>

With this library, you can do this:

var Dropdown = require('form-js').Dropdown;
var dropdown = new Dropdown({
    el: document.getElementsByTagName('select')[0]
});

Which will change your HTML into this:

<div class="dropdown-wrapper">
    <div class="dropdown-container">
        <div class="dropdown-value-container">Virginia</div>
        <div class="dropdown-option-container">
            <div class="dropdown-option" data-value="MD">Maryland</div>
            <div class="dropdown-option dropdown-option-selected" data-value="VA">Virginia</div>
            <div class="dropdown-option" data-value="DC">Washington, DC</div>
        </div>
    </div>
    <select>
        <option value="MD">Maryland</option>
        <option value="VA" selected>Virginia</option>
        <option value="DC">Washington, DC</option>
    </select>
</div>

Then you can style the dropdown using CSS (and just hide the <select> element).

Programmatically change the element's value

Each class comes with a set of utility methods so you can change the elements via JS. Using the example above, you could do the following:

// set the selected value programmatically
dropdown.setValue('DC');

// get the new data value
dropdown.getValue(); // => "DC"

// get the display value
dropdown.getDisplayValue(); // => "Washington, DC"

Listening to change events

You can also listen to events on form elements. Given the following input element...

<input type="text" value="" placeholder="Enter text here" />

You can do the following:

var InputField = require('form-js').InputField;
var inputField = new InputField({
    el: document.getElementsByTagName('input')[0],
    onChange: function (el) {
        // user has finished typing into the field!
    },
    onKeyDownChange: function (el) {
        // the user has typed a key into the field!
    }
});
// set the value
inputField.setValue('My text'); // set new value
// get the new value
inputField.getValue(); // => "My text"

Detect when user changes any value in a form

Suppose you have this HTML:

<form class="debt-info-form">
    <input type="text" name="first_name" value="" />
    <select name="loan_type">
        <option value="CC">Credit Card</option>
        <option value="Mortgage">Mortgage</option>
        <option value="HELO">HELO</option>
        <option value="Student Loan">Student Loan</option>
    </select>
</form>

You can detect when a user changes any of the form's elements like so:

var Form = require('form-js').Form;
var form = new Form({
    el: document.body.getElementsByClassName('debt-info-form')[0],
    onValueChange: function (val, el) {
        // a value has been changed!
       console.log('new value: ' + val);
    }
});
form.setup();

Examples

Examples can be found in the examples page.

API Documentation

Form

The form class allows you to instantiate an entire form (along with its nested elements: <input>, <textarea>, <select>).

Form.constructor

To create an instance of a form, you need to pass the form element (and a set of options if you'd like).

let formElement = document.getElementByTagName('form')[0];
var form = new Form({
   el: formElement
});

Form.setup()

Setup just does a few standard setup tasks, like bind event listeners and such. This method is necessary after instantiation in order to begin working with your form instance.

Form.getCurrentValues()

A utility method to grab a serialized object of all of the form elements and their current values. See below.

<form id="my-form">
    <input type="text" name="location" value="Arlington, VA" required />
</form>

let formElement = document.getElementById('my-form');
var form = new Form({
   el: formElement
});
form.setup();
console.log(form.getCurrentValues());

/*
[{
    disabled: false,
    name: "location",
    required: false,
    value: "Arlington, VA"
}]
*/

Form.clear()

Clears all fields inside of the form. It also unchecks any checkboxes and resets any dropdown selections.

<form id="my-form">
    <input type="text" id="location-input" name="location" value="Arlington, VA" required />
    <input type="text" id="name-input" name="name" value="John Smith" required />
    <input type="number" name="age" value="Arlington, VA" required />
</form>

let formElement = document.getElementById('my-form');
let locationInput = document.getElementById('location-input');
let nameInput = document.getElementById('name-input');
var form = new Form({
   el: formElement
});
form.setup();
locationInput.value // => "Arlington, VA"
nameInput.value // => "John Smith"
form.clear();
locationInput.value // => ""
nameInput.value // => ""

Form.disable()

Disables all form elements.

Form.enable()

Re-enables all form elements.