Lightweight form class with error handling, validation, and ajax requests (using unfetch)
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FormSpine Logo


FormSpine is a lightweight (~4kb, ~1.2kb gzipped) JavaScript form library with validation, error handling and fetch (Polyfilled with developit/unfetch)

It's promise-based, which makes running scripts on error/success very easy.

Table of Contents

Getting Started

Install Instructions

Adding FormSpine to your project requires NPM. Optinally you could use Yarn.

Run the following command in your project root:

npm install formspine --save

Or with Yarn:

yarn add formspine

Using In Your Project

Using Rollup or WebPack (or another module bundler), you can do like this:

// ES6
import FormSpine from "formspine";

// CommonJS
var FormSpine = require("formspine");

Remember to polyfill Fetch


It's also on unpkg:

<script src="//"></script>

var FormSpine = formspine; // to fix name in UMD package, for consistency.

new FormSpine('/', {});

Please notice that the fetch polyfill is NOT included in the UMD version.


Vue.js example

let fields = {
    todo_text: {
        required: true,
        max_length: 50

new Vue({
    el: "#app",
    data: {
        form: new FormSpine('/create-todo', fields)
    methods: {
        submit: function() {
   => alert('Done!'));


The FormSpine Class

The FormSpine class is the backbone of FormSpine and the class you'll be using.


Method Description Parameters
post Sends a POST request to the url specified in the Form object
delete Sends a DELETE/DESTROY request to the url specified in the Form object
put Sends a PUT request to the url specified in the Form object
submit Sends a request with the type specified, to the url specified in the Form object type: Any request type possible in the fetch api. Example: form.submit('GET')


Name Type Description Required Default
url string The url that requests should be send to. true ''
fields object The fields in the form. true {}
options object An object with additional options false {}
FormSpine options parameters
Name Type Description Required Default
messages object Custom error validation messages. false {}
resetOnSuccess boolean Determines if form fields should be cleared on success. false false
headers object Adds custom headers to each request false {}

The url parameter is the first of three parameters, and it defines which url to send requests to upon submitting. It can be an absolute or relative url, such as: /submit or


The fields that you have in the form should be defined here as an object of objects, keyed by field name. This is also where you define validation rules (if any)


let fields = {
    username: {
        required: true
    password: {
        required: true,
        min_length: 6,
        must_match: "password_confirmation"
    password_confirmation: {
        required: true

// Init form
let formObject = new FormSpine('/submit', fields);

Possible field attributes are:

Name Type Description Default
value string The initial value of the field ''
name string The field name used in error messages (:field) object key name
required boolean Validation rule: determines if field is required false
min_length integer Validation rule: sets a minimum length for the field
max_length integer Validation rule: sets a maximum length for the field
no_digits boolean Validation rule: may not contain digits false
only_digits boolean Validation rule: may only contain digits false
checked boolean Validation rule: has to be checked / be true (for checkbox/radio inputs) false
must_match string Validation rule: has to match another field (good for password confirmations) ``
regex string/regex Validation rule: must match regex

This parameter is useful if you want to translate or change the validation messages. You have to pass in an object of strings with error messages.

Example (Using defaults):

let customMessages = {
    checked:      "The :field must be checked.",
    regex:        "The :field field is invalid.",
    required:     "The :field field is required.",
    no_digits:    "The :field field may not contain digits.",
    only_digits:  "The :field field may only contain digits.",
    must_match:   "The :field field match the :must_match field.",
    min_length:   "The :field field must be at least :min_length characters.",
    max_length:   "The :field field must not be longer than :max_length characters."

// Init form
let formObject = new FormSpine('/submit', {}, { messages: customMessages });


Vue Demo

Preact Demo

Angular Demo


Don't care about client-side validation, and does every byte count? How about using Phalange?

It's a ~0.7kb version of FormSpine, without the Validation library. It still handles errors, but will not validate fields.

Get Phalange here


I found myself creating similar classes for every new project I started, so I felt it was time to combine everything into a single class that I could use for almost all my projects. Of cause, in the nature of sharing, I decided to open source it.

FormSpine is inspired heavily on laracasts/vue-forms

If you're into learning, you should really go signup at Laracasts

Build scripts (and more) are heavily based on developit/unfetch.