Understanding Props in Svelte: A Comprehensive Guide

Introduction to Props

In Svelte, props (short for properties) are a mechanism to pass data from a parent component to a child component. This approach allows developers to create dynamic and reusable components, enhancing the overall functionality of their applications.

Key Concepts

• Props Declaration: Props are declared in the child component using the export keyword, which makes the variable accessible to the parent component.
• Passing Props: Props are passed to child components when they are invoked in the parent component’s markup.
• Default Values: Default values can be set for props, which will be used if no value is provided from the parent.

How to Declare Props

Step 1: Create a Child Component

In your Svelte child component, you declare props like this:

<script>
  export let name; // Declare a prop called 'name'
</script>

<p>Hello {name}!</p>

Step 2: Use the Child Component in Parent

In the parent component, you can pass a value to the child component as follows:

<script>
  import ChildComponent from './ChildComponent.svelte';
</script>

<ChildComponent name="Alice" />

Step 3: Using Default Props (Optional)

You can also provide a default value for a prop, ensuring a fallback is available:

<script>
  export let name = 'Guest'; // Default value
</script>

<p>Hello {name}!</p>

If no name is provided, it will display Hello Guest!.

Conclusion

Declaring and using props in Svelte is a straightforward process that significantly enhances component reusability. By exporting variables in child components, data can effortlessly flow from parent components, making your application more dynamic and interactive.

Key Takeaway

• Use export let to declare props in child components.
• Pass props from parent components to customize child behavior and display.