Svelte offers different ways for components to communicate with each other, including props, slots, etc. You will need to integrate slots to create flexible and reusable components in your Svelte applications.
Understanding Slots in Svelte
Slots inthe Svelte frameworkwork similarly toslots in Vue. They provide a way to pass content from a parent to a child component. With slots, you can define placeholders within a component’s template where you can inject content from a parent component.
This content can be plain text,HTML markup, or other Svelte components. Working with slots enables you to create highly customizable and dynamic components that adapt to different use cases.
Creating a Basic Slot
To create a slot in Svelte, use theslotelement within a component’s template. Theslotelement is a placeholder for the content you will pass from the parent component. By default, the slot will render any content passed to it.
Here is an example of how to create a basic slot:
The code block above represents a child component that uses the slot element to get content from a parent component.
To pass content from a parent component to a child component, you will first import the child component into the parent component. Then, instead of using a self-closing tag to render the child component, use an opening and closing tag. Finally, within the component’s tags, write the content you want to pass from the parent-to-child component.
For example:
In addition to passing content from the parent-to-child components, you’re able to provide fallback/default content in the slots. This content is what the slot will display if the parent component does not pass any content.
Here is how you can pass a fallback content:
This code block provides the text “Fallback Content” as a fallback content for the slot to display if the parent component doesn’t provide any content.
Passing Data Across Slot With Slot Props
Svelte allows you to pass data to slots using slot props. You use the slot props in situations where you want to pass some data from the child component to the content you are slotting in.
The code block above represents a Svelte component. Within thescripttag, you declare the variablemessageand assign the text “Hello Parent Component!” to it. You also pass the message variable to the slot propmessage. This makes the message data available to the parent component when it injects content into this slot.
Thelet:messagesyntax allows the parent component to access themessageslot prop that the child component provides. Thedivtag’smessagevariable is the data from themessageslot prop.
Note that you’re not limited to a single slot prop, you can pass multiple slot props as required:
In the parent component:
Working With Named Slots
You can use named slots when you want to pass multiple slots in your components. Named slots make it easier to manage various slots, as you can give each slot a unique name. With named slots, you can build complex components with varying layouts.
To create a named slot, pass anameprop to theslotelement:
In this example, there are two named slots, the slot namedheaderand the slot namedfooter. Using theslotprop, you’re able to pass content to each slot from the parent component.
This code demonstrates how you use theslotprop to pass content to named slots. In the firstspantag, you pass theslotprop with the valueheader. This ensures that the text within thespantag will render in theheaderslot. Similarly, the text within thespantag with theslotprop’s valuefooterwill render in thefooterslot.
Understanding Slot Forwarding
Slot forwarding is a feature in Svelte that allows you to pass content from a parent component through a wrapper component into a child component. This can be very useful in cases where you want to pass content from unrelated components.
Here is an example of how to use slot forwarding, first create the child component:
Next, you create the wrapper component:
In this code block, you are passing another named slot into themessageslot of the child component.
Then, in the parent component, write this code:
In the above structure, the content “This is from the parent component” gets passed through the wrapper component and directly into the child component thanks to thewrapperMessageslot inside the wrapper component.
Make Your Life Easier With Svelte Slots
Slots are a powerful feature in Svelte that allows you to create highly customizable and reusable components. You have learned how to create basic slots, named slots, use slot props, etc. By understanding the different types of slots and how to use them, you can build dynamic and flexible user interfaces.
