Javascript

Handling Forms in Svelte

Published Jul 6, 2021

Updated Feb 14, 2023

7 min read

This article was written over 18 months ago and may contain information that is out of date. Some content may be relevant but please refer to the relevant official documentation or available resources for the latest information.

Handling Forms in Svelte

If you're building an app or website, it's very likely that at some point you need to add a form to it.

In this post, we'll dive into how to handle forms in Svelte, starting from a simple approach. Then, we'll start adding complexity to it, and finally, we'll have a reusable solution.

Starting with a simple form

Let's build a sign-in form with two fields: email and password.

We'll begin by creating a new Svelte project (I prefer vite).

npm init @vitejs/app

✔ Project name: · forms-in-svelte
✔ Select a framework: · svelte
✔ Select a variant: · svelte-ts

cd forms-in-svelte
pnpm install //use the package manager you prefer
pnpm run dev

NOTE: At the moment of writing there's a bug with Svelte TypeScript projects. If you get an error, add "type":"module" in your package.json file.

Now that we have our application ready, we'll start by removing the content of App.svelte and create a sign-in form.

We should also delete the Counter component created by default.

<!-- App.svelte -->
<main>
  <form>
    <div>
        <label for="name">Email</label>
        <input
          type="text"
          id="email"
          name="email"
          value=""
        />
    </div>
    <div>
      <label for="name">Password</label>
      <input
        type="password"
        id="password"
        name="password"
        value=""
      />
  </div>
    <button type="submit">Submit</button>
  </form>
</main>

<style>
   * {
      box-sizing: border-box;
    }
    form {
      display: flex;
      flex-direction: column;
      width: 300px;
    }

    form > div{
      display: flex;
      justify-content: space-between;
    }

    form > div + * {
      margin-top: 10px;
    }
</style>

Handling the submit event

Currently, our form does nothing. We need to handle the submit event on the form. To do that, we must add a handler.

To handle a submit event, we need to add to the form element the on:submit handler.

For now, we will only parse the form, and print it in the console.

<!-- App.svelte -->
<script lang="ts">
  function onSubmit(e) {
    const formData = new FormData(e.target);

    const data = {};
    for (let field of formData) {
      const [key, value] = field;
      data[key] = value;
    }
    console.log(data)
  }
</script>

<main>
  <form on:submit|preventDefault={onSubmit}>
   <!-- ... -->
  </form>
</main>
<!-- ... -->

Note that we used the event modifier |preventDefault. This is equivalent to adding the Event preventDefault method in the handler.

Adding validation

Now that our form "works", we can add more features to it. For example, we may want to add some validation when the form is submitted. We will make both inputs required. If the form is invalid, we will print an error in the console. Otherwise, we will print the form data.

<!-- App.svelte -->
<script lang="ts">
  function isFormValid(data: {[fieldName: string]: any}): boolean {
    if(!isRequiredFieldValid(data.email)){
      return false
    }

    if(!isRequiredFieldValid(data.password)){
      return false
    }
    return true
  }

  function isRequiredFieldValid(value){
    return value != null && value !== ""
  }

  function onSubmit(e) {
    const formData = new FormData(e.target);

    const data: any = {};
    for (let field of formData) {
      const [key, value] = field;
      data[key] = value;
    }
    if(isFormValid(data)){
      console.log(data)
    } else {
      console.log("Invalid Form")
    }
  }
</script>
<!-- ... -->

Displaying errors

Now, our form is running a simple validation on submit, but we are missing feedback for the user. It's time to display some errors in case something fails.

<!-- App.svelte -->
<script lang="ts">
  let errors: { [inputName: string]: any } = {};

  function isFormValid(data: { [inputName: string]: any }): boolean {
    return !Object.keys(errors).some((inputName) =>
      Object.keys(errors[inputName]).some(
        (errorName) => errors[inputName][errorName],
      ),
    );
  }

  function validateForm(data: { [inputName: string]: any }):void {
    if (!isRequiredFieldValid(data.email)) {
      errors['email'] = { ...errors['email'], required: true };
    } else {
      errors['email'] = { ...errors['email'], required: false };
    }

    if (!isRequiredFieldValid(data.password)) {
      errors['password'] = { ...errors['password'], required: true };
    } else {
      errors['password'] = { ...errors['password'], required: false };
    }
  }

  function isRequiredFieldValid(value) {
    return value != null && value !== '';
  }

  function onSubmit(e) {
    const formData = new FormData(e.target);

    const data: any = {};
    for (let field of formData) {
      const [key, value] = field;
      data[key] = value;
    }

    validateForm(data);

    if (isFormValid(data)) {
      console.log(data);
    } else {
      console.log('Invalid Form');
    }
  }
</script>

<main>
  <form on:submit|preventDefault={onSubmit}>
    <div>
      <label for="name">Email</label>
      <input type="text" id="email" name="email" value="" />
      {#if errors.email && errors.email.required}
        <p class="error-message">Email is required</p>
      {/if}
    </div>
    <div>
      <label for="name">Password</label>
      <input type="password" id="password" name="password" value="" />
      {#if errors.password && errors.password.required}
        <p class="error-message">Password is required</p>
      {/if}
    </div>
    <button type="submit">Submit</button>
  </form>
</main>

<style>
  /* ... */

  form > div {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
  }

  /* ... */

  .error-message {
    color: tomato;
    flex: 0 0 100%;
    margin: 0 2px;
    font-size: 0.8em;
  }
</style>

First, I created an error object to keep track of each field, and its errors. I created it as an empty object as I expect it to be populated when verification happens.

Three functions will help validation:

isRequiredFieldValid checks if a given value is null, undefined, or an empty string.
validateForm sets errors to true or false for each form input. In this example, we are checking if both required fields are valid.
isFormValidwill check if there's an error in the form.

In the template, error messages are added below each form input, with a message to be displayed if the error is present and true.

Finally, some CSS was added for styling the form.

The result looks something like this:

Preparing for reusability

We have a working form right now, but it would be better if somehow we could make our form reusable.

The pattern will be repeated for each input we add. It would be nice if we could make it configurable, or if we could easily add more errors and validators without repeating ourselves.

Let's move the validators to a new file, and add more information to the response.

// Validators.ts
export interface ValidatorResult {
  [validatorName: string]: {
    error: boolean;
    message?: string;
  };
}

export type ValidatorFn = (value: any) => ValidatorResult;

function required(value: any): ValidatorResult {
  if (value === '' || value == null) {
    return { required: { error: true, message: 'Field is required' } };
  }
  return { required: { error: false } };
}

export const Validators = {
  required,
};

Previously, we had the isRequiredFieldValid method returning just a boolean. Now it returns an object with the error name required, error status, and a message, but can be extended with more information if required.

We now need to make use of this new Validator in our App component.

<!-- App.svelte -->
<script lang="ts">
  import { Validators } from './lib/Validators';
  import type { ValidatorFn, ValidatorResult } from './lib/Validators';

  let errors: { [inputName: string]: ValidatorResult } = {};

  let form: {
    [inputName: string]: {
      validators: ValidatorFn[];
    };
  } = {
    email: {
      validators: [Validators.required],
    },
    password: {
      validators: [Validators.required],
    },
  };

  function isFormValid(): boolean {
    return !Object.values(errors).some((field) =>
      Object.values(field).some((errorObject) => errorObject.error),
    );
  }

  function validateForm(data: { [inputName: string]: any }): void {
    Object.keys(data).forEach((field) => validateField(field, data[field]));
  }

  function validateField(field, value) {
    form[field]?.validators &&
      form[field].validators.forEach((fn) => {
        const error = fn(value);
        errors[field] = { ...errors[field], ...error };
      });
  }

  function onSubmit(e) {
    const formData = new FormData(e.target);

    const data: any = {};
    for (let field of formData) {
      const [key, value] = field;
      data[key] = value;
    }

    validateForm(data);

    if (isFormValid()) {
      console.log(data);
    } else {
      console.log('Invalid Form');
    }
  }
</script>

<main>
  <form on:submit|preventDefault={onSubmit}>
    <div>
      <label for="name">Email</label>
      <input type="text" id="email" name="email" value="" />
      {#if errors?.email?.required?.error}
        <p class="error-message">Email is required</p>
      {/if}
    </div>
    <div>
      <label for="name">Password</label>
      <input type="password" id="password" name="password" value="" />
      {#if errors?.password?.required?.error}
        <p class="error-message">Password is required</p>
      {/if}
    </div>
    <button type="submit">Submit</button>
  </form>
</main>

<!-- ... -->

First, I've created a form object that contains the different input names with a list of the validators that should be checked for each of them.

I added the required validator for both of them.

Then we will run all validators in the form object where the key matches the name of the input element.

The template has been updated too to handle the validator response object.

With this small refactoring, we've preserved our previous behavior, but opened the door to expand our form.

More validators

Let's add another validator to our password input.

We'll check if the password has a minimum length of 6 characters.

We'll start by creating a new validator. The best way is to use a higher-order function to set up the length, and return our validator function from it.

export interface ValidatorResult {
  [validatorName: string]: {[key:string]:any} & {
    error: boolean;
    message?: string;
  };
}

// ...

function minLength(number) {
  return function (value): ValidatorResult {
    if (value == null || value.length < number) {
      return {
        minLength: {
          error: true,
          value: number, 
          message: `Field minimum length is ${number}`,
        },
      };
    }
    return { minLength: { error: false } };
  };
}

export const Validators = {
  required,
  minLength
};

Now, we need to add it to our form configuration object, and handle the error in the template. We are using the error default message.

<!-- App.svelte -->
<script lang="ts">
// ...
  let form: {
    [inputName: string]: {
      validators: ValidatorFn[];
    };
  } = {
    email: {
      validators: [Validators.required],
    },
    password: {
      validators: [Validators.required, Validators.minLength(6)],
    },
  };

 //...
</script>

<main>
  <form on:submit|preventDefault={onSubmit}>
   <!-- ... -->
    <div>
      <label for="name">Password</label>
      <input type="password" id="password" name="password" value="" />
      {#if errors?.password?.required?.error}
        <p class="error-message">Password is required</p>
      {/if}
	  {#if errors?.password?.minLength?.error}
        <p class="error-message">{errors.password.minLength.message}</p>
      {/if}
    </div>
    <button type="submit">Submit</button>
  </form>
</main>

<!-- ... -->

Handling other form events

I want to add another feature to our form. I want to validate each field separately on blur.

We can use an event handler with one of each input element to do it.

<!-- App.svelte -->
<script lang="ts">
  //...

  function onBlur(e){
    validateField(e.target.name, e.target.value)
  }

</script>

<main>
  <form on:submit|preventDefault={onSubmit}>
    <!-- ... -->
      <input type="text" id="email" name="email" value="" on:blur={onBlur} />
    <!-- ... -->
      <input type="password" id="password" name="password" value="" on:blur={onBlur} />
       <!-- ... -->
  </form>
</main>

<!-- ... -->

We just added an on:blur event handler, and onBlur method to take care of everything. Now, everytime an input loses focus it will be validated.

Our form is working as expected. However, I'd like to move it to a new component.

Creating a reusable form component

Let's create a new component Form.svelte, and move most of the form logic into it.

The form configuration should remain in the App component, and be passed into the new Form component.

<!-- Form.svelte -->
<script lang="ts">
  import { setContext } from 'svelte';
  import type { ValidatorFn, ValidatorResult } from './Validators';
  import { createEventDispatcher } from 'svelte';
  import { writable } from 'svelte/store';

  export let form: {
    [inputName: string]: {
      validators: ValidatorFn[];
    };
  } = {};

  let formEl;

  const dispatch = createEventDispatcher();
  let errors = writable({});

  function onBlur(e) {
    validateField(e.target.name, e.target.value);
  }

  function isFormValid(): boolean {
    return !Object.values($errors).some((field) =>
      Object.values(field).some(
        (errorObject: ValidatorResult) => errorObject.error,
      ),
    );
  }

  function validateField(field, value) {
    form[field]?.validators &&
      form[field].validators.forEach((fn) => {
        const error = fn(value);
        errors.update((e) => {
          e[field] = { ...e[field], ...error };
          return e;
        });
      });
  }

  function validateForm(data: { [inputName: string]: any }): void {
    Object.keys(data).forEach((field) => validateField(field, data[field]));
  }

  function onSubmit(e) {
    const formData = new FormData(e.target);

    const data: any = {};
    for (let field of formData) {
      const [key, value] = field;
      data[key] = value;
    }
    validateForm(data);

    return dispatch('submit', { valid: isFormValid(), data });
  }

  export function reset() {
    formEl.reset();
  }

  setContext('form', { errors, onBlur });
</script>

<form on:submit|preventDefault={onSubmit} bind:this={formEl}>
  <slot />
</form>

<style>
  form {
    display: flex;
    flex-direction: column;
    width: 300px;
  }

  :global(form > div) {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
  }

  :global(form > div + *) {
    margin-top: 10px;
  }
</style>

The template is very simple. A form element with a slot.

We are also binding the form element, and the on:submit event.

There's only one input: form, which will be in charge of passing data from the parent component.

The element's binding will be used to expose the native reset method from the form element. And the event binding will be used to perform validations, and emit a new submit event to be handled by the parent component.

One important thing to notice is that, to communicate the slotted elements with the Form component, we will use the Context API. There's one caveat though, context is not reactive. But, we can make it reactive by making its content a store.

Currently, we will only need to pass two things to the slotted content, the onBlur method, and the errors object. Because we expect the error object to be changing, I rewrote it as a writable store. Note that everything that previously used the errors object will have to use this new store.

To keep the parent component simple (the one containing the form), the form content will be wrapped in new components that will make use of the context API to get the data from the Form component.

Because I want always to have a label for any given field, I'll make it part of the Input component, and because I want to add validation on blur, I'll get the onBlur method exposed by the Form component through the context API.

<!-- Input.svelte -->
<script lang="ts">
  import { getContext } from 'svelte';
  export let type = 'text';
  export let label;
  export let name;
  const { onBlur } = getContext('form');
</script>

<label for={name}>{label}</label>
<input {name} {type} on:blur={onBlur} />

We are closer to getting the same behavior as before, but we are missing the error components. We can wrap all that functionality in a single component, and get the error information through the context API.

<!-- Error.svelte -->
  import { getContext } from 'svelte';
  const { errors } = getContext('form');
  export let message = null;
  export let fieldName;
  export let errorKey;
</script>

{#if $errors?.[fieldName]?.[errorKey]?.error}
  <p class="error-message">{message || $errors[fieldName][errorKey].message}</p>
{/if}

<style>
  .error-message {
    color: tomato;
    flex: 0 0 100%;
    margin: 0 2px;
    font-size: 0.8em;
  }
</style>

We are now reading the value from the errors store to decide if the message should be shown or not.

We are also using a default message from the validator in case no message is provided.

Now that all the pieces are ready, we can update our App component.

<!-- App.svelte -->
<script lang="ts">
  import { Validators } from './lib/Validators';
  import Form from './lib/Form.svelte';
  import Input from './lib/Input.svelte';
  import Error from './lib/Error.svelte';

  let formEl;
  let form = {
    email: {
      validators: [Validators.required],
    },
    password: {
      validators: [Validators.required, Validators.minLength(6)],
    },
  };

  function onSubmit(e) {
    if (e?.detail?.valid) {
      console.log(e.detail.data);
      setTimeout(() => formEl.reset(), 1000)
    } else {
      console.log('Invalid Form');
    }
  }
</script>

<main>
  <Form {form} on:submit={onSubmit} bind:this={formEl}>
    <div>
      <Input label="Email" name="email" />
      <Error
        fieldName="email"
        errorKey="required"
        message="Email is required"
      />
    </div>
    <div>
      <Input label="Password" name="password" />
      <Error
        fieldName="password"
        errorKey="required"
        message="Password is required"
      />
      <Error fieldName="password" errorKey="minLength" />
    </div>
    <button type="submit">Submit</button>
  </Form>
</main>

<style>
  * {
    box-sizing: border-box;
  }
</style>

Our app component now only needs to set up the validators, handle the submit event, and can reset the form if needed.

Extending the form component

Our form component is now exposing just a few things emitted on the submit event, or through the context API, for the slotted components.

Similar to what we've done with the input field, we must extend the functionality for select, radio buttons, checkboxes, or any other form control that we want.

For example, this is how a select component may look like.

<!-- Select.svelte -->
<script lang="ts">
  import { getContext } from 'svelte';
  export let label;
  export let name;
  const { onBlur } = getContext('form');
</script>

<label for={name}>{label}</label>
<select {name} on:blur={onBlur}>
  <slot />
</select>

And this is how it could be used:

<!-- App.svelte -->
<script lang="ts">
  import { Validators } from './lib/Validators';
  import Form from './lib/Form.svelte';
  import Input from './lib/Input.svelte';
  import Error from './lib/Error.svelte';
  import Select from './lib/Select.svelte';

  let form = {
    name: {
      validators: [Validators.required],
    },
    food: {
      validators: [Validators.required],
    },
  };

  let formEl;

  function onSubmit(e) {
    if (e?.detail?.valid) {
      console.log(e.detail.data);
      setTimeout(() => formEl.reset(), 1000)
    } else {
      console.log('Invalid Form');
    }
  }
</script>

<main>
  <Form {form} on:submit={onSubmit} bind:this={formEl}>
    <div>
      <Input label="Name" name="name" />
      <Error
        fieldName="name"
        errorKey="required"
        message="Name is required"
      />
    </div>
    <div>
      <Select label="Favorite food" name="food">
        <option value="chocolate">Chocolate</option>
        <option value="pizza">Pizza</option>
      </Select>
    </div>
    <button type="submit">Submit</button>
  </Form>
</main>
<!-- ... -->

Available Libraries

There are plenty of available libraries for handling forms in Svelte. You can check some of them in this list.

Final thoughts

I hope this step-by-step guide to handling forms helps you find your own solution to handling them, or gives you a better understanding of how other libraries might be working.

This Dot is a consultancy dedicated to guiding companies through their modernization and digital transformation journeys. Specializing in replatforming, modernizing, and launching new initiatives, we stand out by taking true ownership of your engineering projects.

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About the author(s)

Ignacio Falk
I love to learn new things and share what I know. Mentor, Writer, Speaker Member of the local community
@flakolefluk @flakolefluk

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Parsing and Validating Data with Schemas With Zod schemas, you're not only telling your program what data should look like; you're also creating the tools to easily verify that the incoming data matches the schema definitions. This is where Zod really shines, as it greatly simplifies the process of validating data like user inputs or third party API responses. Let's say you're writing a website form to register new users. At a minimum, you'll need to make sure the new user's email address is a valid email address. For a password, we'll ask for something at least 8 characters long and including one letter, one number, and one special character. (Yes, this is not really the best way to write strong passwords; but for the sake of showing off how Zod works, we're going with it.) We'll also ask the user to confirm their password by typing it twice. First, let's create a Zod schema to model these inputs: ` So far, this schema is pretty basic. It's only making sure that whatever the user types as an email is an email, and it's checking that the password is at least 8 characters long. But it is *not* checking if password and confirmPassword match, nor checking for the complexity requirements. Let's enhance our schema to fix that! ` By adding refine with a custom validation function, we have been able to verify that the passwords match. If they don't, parsing will give us an error to let us know that the data was invalid. We can also chain refine functions to add checks for our password complexity rules: ` Here we've chained multiple refine functions. You could alternatively use superRefine, which gives you even more fine grained control. Now that we've built out our schema and added refinements for extra validation, we can parse some user inputs. Let's see two test cases: one that's bound to fail, and one that will succeed. ` There are two main ways we can use our schema to validate our data: parse and safeParse. The main difference is that parse will throw an error if validation fails, while safeParse will return an object with a success property of either true or false, and either a data property with your parsed data or an error property with the details of a ZodError explaining why the parsing failed. In the case of our example data, userInput2 will parse just fine and return the data for you to use. But userInput1 will create a ZodError listing all of the ways it has failed validation. ` ` We can use these error messages to communicate to the user how they need to fix their form inputs if validation fails. Each error in the list describes the validation failure and gives us a human readable message to go with it. You'll notice that the validation errors for checking for a valid email and for checking password length have a lot of details, but we've got three items at the end of the error list that don't really tell us anything useful: just a custom error of Invalid input. The first is from our refine checking if the passwords match, and the second two are from our refine functions checking for password complexity (numbers and special characters). Let's modify our refine functions so that these errors are useful! We'll add our own error parameters to customize the message we get back and the path to the data that failed validation. ` Now, our error messages from failures in refine are informative! You can figure out which form fields aren't validating from the path, and then display the messages next to form fields to let the user know how to remedy the error. ` By giving our refine checks a custom path and message, we can make better use of the returned errors. In this case, we can highlight specific problem form fields for the user and give them the message about what is wrong. Integrating with TypeScript Integrating Zod with TypeScript is very easy. Using z.infer<typeof YourSchema> will allow you to avoid writing extra TypeScript types that merely reflect the intent of your Zod schemas. You can create a type from any Zod schema like so: ` Using a TypeScript type derived from a Zod schema does *not* give you any extra level of data validation at the type level beyond what TypeScript is capable of. If you create a type from z.string.min(3).max(20), the TypeScript type will still just be string. And when compiled to JavaScript, even that will be gone! That's why you still need to use parse/safeParse on incoming data to validate it before proceeding as if it really does match your requirements. A common pattern with inferring types from Zod schemas is to use the same name for both. Because the schema is a variable, there's no name conflict if the type uses the same name. However, I find that this can lead to confusing situations when trying to import one or the other—my personal preference is to name the Zod schema with Schema at the end to make it clear which is which. Conclusion Zod is an excellent tool for easily and confidently asserting that the data you're working with is exactly the sort of data you were expecting. It gives us the ability to assert at runtime that we've got what we wanted, and allows us to then craft strategies to handle what happens if that data is wrong. Combined with the ability to infer TypeScript types from Zod schemas, it lets us write and run more reliable code with greater confidence....

Nov 15, 2024

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JavaScriptZod

The Journey To Making A New Framework: TanStack Start with Tanner Linsley

Danny Thompson, Director of Technology at This Dot Labs, talks with Tanner Linsley, Creator of TanStack, about his latest project, TanStack Start. They discuss the challenges of existing frameworks like Next.js and Remix, the development of TanStack Router, and the future of React Server Components. Tanner also explains how caching strategies and fine-grained invalidation can transform the user experience. Chapters - - Introduction & Tanner’s Background (00:00) - Going Full-Time on TanStack (01:00) - The Birth of TanStack Router (02:21) - Why Build Another Framework? (04:00) - React Server Components: Potential & Limitations (07:05) - Fine-Grained Cache Invalidation & UX (09:02) - Parallel Data Fetching in Routing (13:39) - TanStack Start: Alpha & Future Plans (16:41) - Where to Learn More About TanStack (18:48) Find Tanner Linsley on Social Media Twitter: https://x.com/tannerlinsley Linkedin: https://www.linkedin.com/in/tannerlinsley/ Github: https://github.com/tannerlinsley TanStack: https://tanstack.com/ Sponsored by Wix Studio...

Oct 9, 2024

1 min

TanStack QueryJavaScriptReact

Building Mobile Applications with Svelte and NativeScript

Have you ever wanted to build a mobile application using a language you already know? In this tutorial, we'll learn how to start building a mobile application using Svelte and NativeScript. What is NativeScript NativeScript is a framework that will allow you to write Native apps using JavaScript or Typescript and, at the same time, it allows you to access platform-specific Native APIs. Setting up your environment The very first step to developing with NativeScript is installing all the required dependencies. If you're lucky, you'll already have everything installed. But if not, we'll see how to get it to work. The first thing (assuming you already have Node installed) is to install NativeScript globally. ` For this tutorial, I'll be developing an iOS application. The best way to check if your environment is prepared is to use the command provided by NativeScript. ` There's an equivalent command for android if that's your target OS. If you are missing anything, you'll get a bunch of messages with the requirements needed. In my case, I had to install XCode, Ruby, Some Gems, and Python libraries. Please refer to the setup guide to check what you need (macOS + iOS, for me). It's important to have your environment ready. Otherwise, we will not be able to run our project. ` Starting a new project Now that our environment is set up, let's start a new project. We are going to base this example app on this sample from the NativeScript samples page. However, we will add more to it, like including HTTP requests, and a List/Detail navigation. ` The command will create a Svelte + NativeScript project, and install the required dependencies. Our folder structure will look like this: We'll be focusing on the /app folder where our JS/TS will be added. ` ` App.svelte will render the default page Home which contains a message and an icon. You'll notice that these are not the HTML tags you're used to, and that's because these are not HTML elements. These are native elements/views. So if you were thinking of reusing your code in a web app, for example, this is not the part that you'll be able to share. If that's what you need, make sure you extract the pieces that can be reused. Building Our Application Let's delete the content from Home.svelte, and let's talk about what we'll be building. The app we will build will display a list of items, and when clicked, will navigate into a detailed view. The date for this example will be fetched from the PokeAPI. Creating a List view Let´s create our Home page a.k.a the list. But first, let's create some types to be used in our list. ` First, we created a type for the rest API response. It will contain a list of Pokémon with a few properties. We also create a type for the model used in our view. ` Our page consists of a set of layouts and a list view. Each list item will display an image and a label. However, our view is missing data. Integrating with PokeAPI Let's create a service that will fetch a list of Pokémon. ` To make a request I'll use the Http API provided by NativeScript. It contains a set of methods that I recommend you to check out before deciding which one will suit better for your use case. I'm making a little transformation to the received data, to build the URL with the sprite of each item. Once our service is in place, we'll fetch data and display it. By default, we will fetch 100 items starting from the first one. I'll make a request once the item is mounted, which means I'll first render the action bar only, and when the response is received, the list will be rendered. ` Our app should look this by now Much better! Adding the Details view For our sample application to be complete, we want to be able to navigate to a more detailed page of a Pokémon when one list item is selected. First, we need to create our destination component: a detailed view of a Pokémon. We will be adding fetching a description for the Pokémon, but there's a lot of information you can get from the API. Let's add this call to the API service, and create our detailed view. ` ` We will be using a set of stackLayout to build our view, display the image, add the name to the action bar, and finally show a loading message while getting the description, and an error if it fails. Notice there are two properties exported. This means that these properties must be passed as inputs from a parent. Bringing all together It's time to connect the list view, and the details view. Let's see the final Home Page: ` We have now included an event listener (on:itemTap), that will then call the navigate method included in svelte-native. Here, we passed the required props item and index to the Details Component. Now we have connected both views. We don't have to think about a back button in our details view because it's automatically there when you navigate, and add a view to the navigation stack. The final result: Success. Publishing your app If you want to publish the application start by running ns prepare ios --release Open the project in XCode and follow the instructions on how to publish an iOS app. Final words Being able to work on a native application using a language and a framework you're comfortable with can be a benefit. But there's a cost to it. Setting up the environment is not as straightforward as it could be, but thankfully, the CLI makes it a lot easier to diagnose what's required. There's a lot more to explore in NativeScript like using plugins, but it's out of scope for this post, where we explore the usage of Svelte with NativeScript. You can check the code from this tutorial in this repo....

Oct 17, 2022

5 mins

Svelte

Learning Paths for Next.JS Developers with Ankita Kulkarni

In this video, Rob Ocel and co-hosts Tracy Lee, Adam Rackis, and Danny Thompson talk with tech educator Ankita Kulkarni about her journey from engineering leader to full-time educator. Ankita shares insights on teaching Next.js, bridging practical knowledge gaps, and helping developers tackle real-world challenges. They discuss Next.js as a React-based framework, its benefits, and the challenges it presents for beginners. Chapters - Introduction to the Podcast and Guests 00:01 - Meet Ankita Kulkarni, Tech Educator 00:26 - Ankita's Transition to Full-Time Education 01:41 - Teaching Practical Knowledge in Next.js 03:19 - Effective Methods for Teaching Next.js 05:27 - Challenges of Being a Full-Time Educator 07:48 - Balancing Broad and Specific Examples 09:54 - Embracing Mistakes as a Teaching Tool 12:13 - Pair Programming and Mentorship 14:00 - Discussion on Next.js and Framework Adoption 16:48 - Advantages and Challenges of Next.js 18:12 - Choosing the Right Framework for Your Needs 20:35 - Impact of Next.js in React Documentation 22:26 - Learning Paths for New Developers 23:24 - The Rise of Full-Stack Web Development 25:09 - Benefits of Frameworks Abstracting Complexity 26:27 - OpenNext and Deployment Flexibility 28:06 - Ankita's Excitement for New Next.js Features 30:35 - The Future of Next.js Without Vercel 32:16 - Final Thoughts and Where to Find Everyone Online 34:21 Follow Ankita Kulkarni on Social Media Twitter: https://x.com/kulkarniankita9 YouTube: https://www.youtube.com/@kulkarniankita Sponsored by This Dot: thisdot.co...

Nov 12, 2024

2 mins

NextJSJavaScript

Let's innovate together!

We're ready to be your trusted technical partners in your digital innovation journey.

Whether it's modernization or custom software solutions, our team of experts can guide you through best practices and how to build scalable, performant software that lasts.

Handling Forms in Svelte

Handling Forms in Svelte

Starting with a simple form

Handling the submit event

Adding validation

Displaying errors

Preparing for reusability

More validators

Handling other form events

Creating a reusable form component

Extending the form component

Available Libraries

Final thoughts

Ignacio Falk

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