Unlock the Power of Forms in Svelte
Forms are an essential part of web development, and Svelte is no exception. To create robust and user-friendly forms, you need to track user input, validate data, and handle form submissions. In this article, we’ll explore the world of Svelte forms, covering input bindings, validation with Yup, and the benefits of using svelte-forms-lib.
Tracking User Input with Svelte
Svelte provides two directives to track user input: on:input and bind:value. While on:input requires a handleInput event, bind:value offers a cleaner way to work with form values. We’ll use bind:value to simplify our form development process.
Validating Forms with Yup
Yup is a popular JavaScript object schema validator that ensures data conforms to a specific structure. By defining a schema, you can validate objects and guarantee that the data sent to the server is valid. We’ll create a profile form and validate it using Yup’s validate method.
Creating a Profile Form with Svelte
Let’s set up a simple profile form to capture user data. We’ll bind the form fields to a values object and create an errors object to store validation errors. Our handleSubmit function will handle form validation and submission.
Displaying Validation Errors
To display errors, we’ll loop over Yup’s validation error.inner array and create a new object with fields and error messages. We’ll then update the errors object with the corresponding input field errors.
Simplifying Form Development with svelte-forms-lib
Svelte-forms-lib is a Formik-inspired library that makes building forms in Svelte easier. We’ll explore how to integrate svelte-forms-lib into our form, using its createForm function, observables, and helper functions like handleChange and handleSubmit.
Custom Validation with svelte-forms-lib
We’ll learn how to add a custom validation callback to createForm, checking the state of each input field and updating the errors object accordingly.
Yup Validation in svelte-forms-lib
Svelte-forms-lib also supports Yup validation through the validationSchema prop. We’ll pass in our schema object and let svelte-forms-lib handle the validation.
Custom Form Components in svelte-forms-lib
To reduce boilerplate code, svelte-forms-lib provides custom components like <Form/>, <Field/>, <Select/>, and <ErrorMessage/>. We’ll use these components to create a concise and efficient form.
Take Your Forms to the Next Level
In this article, we’ve covered the essential tools and techniques for building robust forms in Svelte. By mastering input bindings, Yup validation, and svelte-forms-lib, you’ll be able to create forms that are both user-friendly and developer-efficient.