Building a To-Do app It has never been easier: Using SvelteKit ūüĒ•

Building a To-Do app It has never been easier: Using SvelteKit ūüĒ•

The Ultimate guide

Jan 15, 2023·

7 min read

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Introduction

SvelteKit is the best framework to build a fast lightweight web apps, this is why I am going to publish a series of posts about svelte and how to build apps with it.

What we going to build:

Today we are building a to-do app using SvelteKit, and we will implement the CURD operation ( Create, Update, Read, Delete).

it will be simple and fast.

Tools

  1. Vite.

  2. SvelteKit

  3. NPM package manager

Setup

GitHub Repo If you want to follow along.

create-svelte

Everything you need to build a Svelte project, powered by create-svelte.

Creating a project

If you're seeing this, you've probably already done this step. Congrats!

# create a new project in the current directory
npx create-vite@latest

Developing

Once you've created a project and installed dependencies with npm install (or pnpm install or yarn), start a development server:

npm run dev

# or start the server and open the app in a new browser tab
npm run dev -- --open

Building

To create a production version of your app:

npm run build

You can preview the production build with npm run preview.

View on GitHub

First, you will write the name of the app, for it will be ‚Äúto-do‚ÄĚ, Second, you have to choose the framework, and we will choose Svelte, After that, we will Choose our variant, which is SvelteKit, It should look like this.

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The Variant.

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After that, you will be asked how you want your app set up make sure the answer is exactly the same as pointed out in the screenshot down.

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Now your app is ready for development.

Fire Up the server

now you need to start the server so follow the given commands bellow

1. $ cd To-do #Your project folder
2. $ npm install # I use 'npm i' only because I am lazy :)
3. $ npm run dev

Your Terminal should be like this.

Image description

Now open your favourite editor, mine is Neovim.

First component: Todo-form

open the src Directory and add a new folder call it components, inside that folder, add a new file and call it Todo-form.svelte, open it, copy the code down below and I will explain every line.

<!-- TodoForm.svelte -->
<script>
    export let addTodo;
    let todoText = '';

    function handleSubmit(event) {
        event.preventDefault();
        addTodo(todoText);
        todoText = '';
    }
</script>

<form class="bg" on:submit|preventDefault={handleSubmit}>
    <input type="text" bind:value={todoText} placeholder="Add a todo..." />
    <button type="submit">Add</button>
</form>

The export let addTodo; export a property named addTodo from the component. This allows the parent component to bind a function to the addTodo property, which will be called when the form is submitted.

The let todoText = ''; declares a local variable named todoText and sets its initial value to an empty string. This variable is used to store the value of the input field.

The handleSubmit(event) function is called when the form is submitted. It is passed an event object representing the form's submission event. Inside the function, the following things happen:

  • event.preventDefault() is used to prevent the browser's default behaviour when a form is submitted, which would be to refresh the page.

  • addTodo(todoText) is called the current value of todoText as an argument. This function is passed into the component via the addTodo property and is expected to handle adding the new todo.

  • todoText = ''; clears the todoText variable, so the input field is ready for the next to-do item.

In the <form> tag, the class="bg" sets the form's background colour to be the background colour. The on:submit|preventDefault={handleSubmit} uses Svelte's event handling system to attach the handleSubmit function as an event handler for the form's submit event, and also prevent the default submission behaviour of the form.

The <input> element has bind:value={todoText} which binds the value property of the input element to the todoText variable so that any changes made to the input field will be reflected in the variable, and vice versa. The placeholder attribute sets a placeholder text for the input field.

The <button type="submit"> has Add as the label for the button which on clicking it triggers the submit event and calls the handleSubmit function.

Second Component: Todo-list:

Now add another file call it Todo-list.svelte , Then copy and paste this code:

<!-- TodoList.svelte --> 
 <script> 
         export let todos = []; 
         export let deleteTodo; 
 </script> 

 {#each todos as todo} 
         <div class="todo"> 
                 <div class="todo-text">{todo.text}</div> 
                 <button class="todo-delete" on:click={() => deleteTodo(todo.id)}> 
Delete 
</button> 
         </div> 
 {/each}

This code is a Svelte component that defines a template for rendering a list of to-do items, as well as an accompanying script. The component accepts two props, todos and deleteTodo.

In the script, the todos and deleteTodo props are declared using the export keyword, indicating that they are expected to be passed down from a parent component.

The template part of the component uses the Svelte's {#each} directive to render a div element for each item in the todos array. Inside the {#each} block, there is another div element with a class of "todo" that contains two children elements.

The first one is a div element with a class of "todo-text" that displays the "text" property of the todo item, And the second one is a button element with a class of "todo-delete" that has an on:click event listener that is triggered when the button is clicked, when it happens, it will call the function passed down in the deleteTodoprop, passing the "id" property of the current to-do item as an argument.

This way, when the button is clicked, it will call the deleteTodo function and pass the id of the todo item, This makes it easy to delete the specific todo item from the list.

Add components to the Main Page

Now we need to add the components to the page we want in order to be rendered to the browser, You will find a folder called routes inside the src folder, open the file inside of it called +page.svelte, I want you to copy this:

<!-- App.svelte -->
<script>
    import TodoList from '../components/Todo-list.svelte';
    import TodoForm from '../components/Todo-form.svelte';

    let todos = [
        { id: 1, text: 'Wellcome' },
        { id: 2, text: 'To' },
        { id: 3, text: 'my Todo' },
        { id: 4, text: 'app' }
    ];
    let text;

    function addTodo(text) {
        todos = [...todos, { id: Date.now(), text }];
    }

    function deleteTodo(id) {
        todos = todos.filter((todo) => todo.id !== id);
    }
</script>

<div class="todo-container">
    <TodoForm {addTodo} />
    <div class="todo-list">
        <TodoList {todos} {deleteTodo} />
    </div>
</div>

<style>
    .todo-list {
        margin-top: 5rem;
    }
    .todo-container {
        max-width: 100vw;
        display: grid;
        place-items: center;
    }
</style>

Explanation

At the top of the script, the code imports two Svelte components: TodoList and TodoForm. These components are likely defined in other files in the same directory.

Then there is a variable called todos which is an array of todo objects with properties id and text
and another variable called text which is empty.

The code also defines two functions:

  1. addTodo function that takes in a parameter called text, create a new todo object with a unique id and the text, and add it to the array of todos.

  2. deleteTodo function that takes an id and filters out the object from the array of todos which have that id.

Then there is a div with the class "todo-container" that contains two elements. One is the TodoForm component, which passed the addTodo function as a prop. The other element is a div with the class "todo-list" that contains the TodoList component.
This component passed two props: {todos} and {deleteTodo} which allows the component to use the array of todos and deleteTodo functions.

The Final step:

open the browser and type in the search bar https://localhost:5173, you should see the result for all the copy and paste up there.

Free

Thank you for reading this post. I hope it helps you and becomes a fan of this framework (SvelteKit). Here are your rewards. A little book about clean code and how to implement it. It's free.

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