Optimizing for production

FormKit ships with a lot of functionality out of the box. This is great for getting started, but the defaultConfig may include features and inputs you aren’t using. In this guide, we'll learn how to slim down our FormKit installation for production.

Examining the defaultConfig

Most FormKit users get started by using the provided defaultConfig — but what does this actually include?

• Adds the @formkit/validation plugin with all rules.
• Adds the @formkit/i18n plugin with the en locale (plus any additional locales you've added).
• Adds the @formkit/inputs plugin with all non-pro inputs.
• Adds the @formkit/theme plugin with CDN-loaded icons, or any explicitly loaded icons.
• Adds the @formkit/vue bindings to allow FormKit to interface with Vue.
• Registers the @formkit/dev error interpreter (gives human-readable error messages in development).

The defaultConfig also exposes a convenient object syntax to provide configuration options for all the plugins above. For example, to provide an input to the @formkit/inputs plugin instantiation, the default config allows you to pass an inputs property:

app.use(plugin, defaultConfig({
  inputs: {
    myInput: createInput(/* input options */)
  }
}))

For more details, check out the source code of the defaultConfig.

A custom configuration

When optimizing your FormKit installation for production, you may want to create a custom configuration. This will allow you to only include the features, inputs, rules, and messages you are actually using.

For example, consider a project with a simple form that only uses a text input and the required rule. Something like this:

<script setup>
async function submit () {
  // ... submit the things
}
</script>
<template>
  <FormKit
    type="form"
    @submit="submit"
  >
    <FormKit
      type="text"
      name="name"
      label="Name"
      help="What do people call you?"
      validation="required"
    />
  </FormKit>
</template>

In this case, we only want to use the singular required rule, only the text input, and only the required message in English and German. We can create this tree-shakable custom configuration by not using the defaultConfig and instead performing our own plugin instantiations:

Using the global plugin

// file: main.ts
import { createApp } from 'vue'
import App from './App.vue'
import type { FormKitOptions } from '@formkit/core'
import { plugin, bindings } from '@formkit/vue'
import { createValidationPlugin } from '@formkit/validation'
import { required } from '@formkit/rules'
import { createI18nPlugin, en, de } from '@formkit/i18n'
import { createLibraryPlugin, text, form, submit } from '@formkit/inputs'

const library = createLibraryPlugin({ text, form, submit })
const validation = createValidationPlugin({ required })
const i18n = createI18nPlugin({ en, de })

const app = createApp(App)
app.use(plugin, {
  plugins: [library, validation, i18n, bindings]
})

Using the Nuxt module

If you are using the @formkit/nuxt module, you can opt out of the defaultConfig by providing the defaultConfig: false option to the module:

export default defineNuxtConfig({
  modules: ['@formkit/nuxt'],
  formkit: {
    autoImport: true,
    defaultConfig: false
  }
})

Then your formkit.config.ts is expected to provide a full custom configuration:

import type { FormKitOptions } from '@formkit/core'
import { bindings } from '@formkit/vue'
import { createValidationPlugin } from '@formkit/validation'
import { required } from '@formkit/rules'
import { createI18nPlugin, en, de } from '@formkit/i18n'
import { createLibraryPlugin, text, form, submit } from '@formkit/inputs'

const library = createLibraryPlugin({ text, form, submit })
const validation = createValidationPlugin({ required })
const i18n = createI18nPlugin({ en, de })

export default {
  plugins: [library, validation, i18n, bindings]
} satisfies FormKitOptions

createI18nPlugin({
  en: {
    validation: {
      required: 'This field is required'
    },
    ui: {
      submit: 'Submit'
    }
  },
  de: {
    validation: {
      required: 'Dieses Feld ist erforderlich'
    },
    ui: {
      submit: 'Einreichen'
    }
  }
})

Configuration injection (code splitting)

Vue’s plugin architecture is inherently global. The plugin in @formkit/vue is no different; however, this convenience comes with a cost — FormKit will be loaded wherever Vue is loaded, even if it is not used on the page.

Fortunately for Nuxt users, the @formkit/nuxt module provides a solution to this problem: autoImport: true. This option will automatically inject FormKit and its configuration only on pages where it is used.

Vite users can also leverage automatic injection by using unplugin-formkit.

For users of other build tools or for use cases that don’t fit well within the supported features of unplugin-formkit, using the <FormKitProvider> component allows you to provide global configuration to your FormKit inputs at the point of use. Wrap your components in <FormKitProvider> and provide a config prop:

<script setup>
import { FormKitProvider } from '@formkit/vue'
import type { FormKitOptions } from "@formkit/core"

const formKitConfig: FormKitOptions = {
  // ... your custom config
}
</script>

<template>
  <FormKitProvider :config="formKitConfig">
    <!-- your FormKit components (can be deeply nested) -->
  </FormKitProvider>
</template>