antoninadert / svelte-validator

Validation library for Svelte v3 application

svelte-validator

Install

This is WIP project. Use at your own responsibility!

npm i -S svelte-validator

Usage

<script>
  import createValidator, { required, minLength, hasError } from 'svelte-validator'

  const [valueStore, errorStore, command] = createValidator({
    initial: '',
    rules: [
      required({ message: 'Cannot be blank!' }), // Can put arbitrary object
      minLength(3, { message: 'Should be longer than 3.' }),
    ]
  })
</script>

<form>
  <input bind:value="{$valueStore}">
  {#if 'required' in $errorStore}
    <span>{$errorStore.required.message}</span>
  {/if}
  {#if 'minLength' in $errorStore}
    <span>{$errorStore.minLength.message}</span>
  {/if}

  <button type="submit" disabled="{hasError($errorStore)}">Submit</button>
</form>

createValidator Options

rules

An array of validators.

initial

Initial value of valueStore.

immediate

If false, validation does not run until calling command.activate(). Default true. For example this can be used to prevent display errors until first blur event occurs.

<input type="text" on:blur="{command.activate}">

Builtin Validators

• required(options)
• minValue(min, options)
• maxValue(max, options)
• betweenValue([min, max], options)
• minLength(length, options)
• maxLength(length, options)
• betweenLength([min, max], options)
• format(regex, options)

You can put any object on options. It can be accessed via errorStore like $errorStore.minValue. See implementation for more details.

Custom Validator

You can implement your own validator. It should be an object which has name and isValid properties, and optionally options.

const myRule = {
  name: 'myRule',
  isValid: (value) => {
    // true or false
  },
  options: {},
}

const [valueStore, errorStore] = createValidator({ rules: [myRule] })
// $errorStore.myRule appears when value violates the rule.