📛 Automatically Name Selected Elements
The <AutoNameSelected /> component can assign view-transition-names to elements based on a CSS selector.
Contents
Why should I use this component?
There are situation where you are not able or do want to set view-transition-name CSS properties automatically for your elements. This is regularly the case when the set of elements is not statically known or you do not have full control over the HTML, because you generate it from something else, e.g. Markdown.
Example
The image gallery demo uses the AutoNameSelected component to create morph effects when navigating from one page with an image gallery to the next. On navigation, it assigns a view-transition-name to each image in the current gallery and the same set of names to the images on the next page. The order of names is randomized to achieve a “pictures morph all over the place” effect.
Usage
Install astro-vtbot in your project as an Astro integration with npx astro add astro-vtbot or as a node package with npm install astro-vtbot.
The recommended way is to place the <AutoNameSelected /> component in your basic layout after the <ViewTransitions /> component.
---import { ViewTransitions } from 'astro:transitions';import AutoNameSelected from 'astro-vtbot/components/AutoNameSelected.astro';---<html> <head> <ViewTransitions /> <AutoNameSelected prefix="image" selector="main .gallery img"/> ... </head> ...</html>Properties
The component has properties that you can use to target it on what elements to name and what name to use. You can also decided if you want to override existing view-transition-name or if elements that already have an view transition name should be ignored.
| Property | Type | Default | Effect |
|---|---|---|---|
| selector | string | ’h1, h2, h3, h4, h5, h6’ | Instructs the <AutoNameSelected> component to give view-transition-names to all elements identified by this CSS selector. The selector must not be the empty string. |
| force | boolean | true | By default view-transition-names are given to all selected elements. If you set force={false}, elements that already have a style.viewTransitionName are exempt. |
| prefix | string | ’vtbot-hx’ | This value is used to construct the names. The names are created by adding a dash and a number to the prefix. With the default, the component generates names vtbot-hx-0, vtbot-hx-1, … An exception are the empty string and the value ‘none’, which will be used without adding anything. Do only use characters from this set: A-Za-z-_ |
| shuffle | boolean | false | If this property is set to true, AutoNameSelected will name the selected elements in some random order. Otherwise they are named in the order returned by querySelectorAll() which is depth-first pre-order. |
You can use this component to clear view transition names if you explicitly set the prefix to the empty string.
You can have multiple instances of this component on your layout / on a page. They are all applied in order. If the selector does not select any elements, the component has no effect on the page.
The component needs to be on both pages, the from page and the to page of a navigation. Config options can be different on both pages.
Avoid adding the same view transition names to the same DOM twice using this component. That will break the view transition due to the non-unique names. Typical situations for this are:
- You are using
transition:persist/data-astro-transition-persistand your selector selects a persisted element. - You are using the
ReplacementSwapcomponent and your selector selects an element outside anydata-vtbot-replacetree.
Use simple selectors like img to select all images on all pages. Or use some elaborated CSS to exactly target the effect:
selector='head:has(link[rel="canonical"][href^="/jotter/"]) + body main :is(h1, h2, h3, h4, h5, h6)'This is what I use to name all headings in the <main> area, but only on the pages of the Jotter.