Automatic updates with observe

Applies to components and directives.

observe controls automatic image DOM observation and how often the gallery updates. It watches additions, removals, reordering and attribute changes (such as src and alt) of <img> elements inside the container, including images replaced by rendered Markdown or HTML. Unrelated text, container styling and Viewer.js-generated UI do not trigger gallery updates.

Value	Behavior	Suitable for
true (default)	Start a 50ms window at the first image mutation and update once for changes within that window.	Markdown, HTML or images rendered in successive batches.
0	Add no batching delay, but still update asynchronously. Mutations received before that update runs are combined.	Infrequent changes that should appear promptly.
A positive number, such as 100	Batch mutations within the specified number of milliseconds.	Frequent changes, especially with rebuild enabled.
false	Disable automatic image DOM observation. Initial creation, configuration changes and manual update() calls still work.	Fixed content or manually controlled updates.

For example, adding 10 <img> elements in one synchronous operation can produce a single update even with 0. Adding them in separate asynchronous operations may produce multiple updates with 0, while 50 combines mutations within the same 50ms window.

The window starts at the first image mutation and is not restarted by later mutations, allowing continuously changing galleries to update periodically. Initial creation is immediate; the delay applies only to subsequent automatic image DOM updates.

By default, each batch reuses the instance and calls update(). With rebuild enabled, it destroys and recreates the instance instead. observe can change reactively; setting it to false cancels any pending automatic update.