Data isn’t always there. An editor skips the subtitle, a blog post has no author image, a showtime sells out. Handle those gaps gracefully and nobody notices. Handle them badly, by forgetting a fallback or padding layout with empty DOM nodes, and you’ve quietly broken the page for screen reader and keyboard users.
Data-driven conditional content is interface content that is rendered, hidden, updated, or removed based on the state of a data value. Think null, undefined, counts of 0, empty strings, or missing object keys that come from the data, not from something a user did.
For example, a showtime sells out so the button to buy tickets is removed, or a blog post has no author image so a generic avatar is used instead. The pitfalls arrive when developers don’t handle those gaps gracefully.