> ## Documentation Index
> Fetch the complete documentation index at: https://docs.reader.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Waiting for dynamic content

> Use waitForSelector when content is hydrated client-side after initial load.

Modern single-page apps don't render content until JavaScript runs and data arrives. If you scrape the initial HTML you get a skeleton: loading spinners, empty divs, maybe a `<noscript>` fallback. You want what the page looks like *after* hydration.

## The `waitForSelector` option

Tell Reader to wait for a specific element to appear before capturing:

```ts theme={null}
const result = await reader.read({
  url: "https://shop.example.com/search?q=phone",
  waitForSelector: ".product-card",
});
```

Reader loads the page, waits for `.product-card` to exist in the DOM, then captures the content. If the selector shows up within `timeoutMs` (default 30 seconds), you get the post-hydration page. If not, the scrape times out.

## Picking the right selector

Open the target page in your browser. Wait for it to fully load. Pick a selector that's:

* **Inside** the content you care about (so you know the real content has arrived, not just the shell)
* **Stable** across page variants (if you're scraping many similar URLs)
* **Late-loading** (it should only appear once the hydration has actually completed)

Bad selectors:

* `body`: already exists before hydration, won't wait for anything
* `.loading-spinner`: the opposite of what you want (would match *during* loading)
* `#some-unique-id-that-changes-every-request`: won't match across pages

Good selectors:

* `[data-testid="product-list"]`: stable, semantic, only present post-hydration
* `article .content`: semantic, broad enough to work across similar pages
* `.search-results[data-loaded="true"]`: explicitly gated on a loaded flag

## When `waitForSelector` isn't enough

Some pages are hard for reasons selectors can't fix:

* **Infinite scroll.** The content you want only appears after scrolling. Reader doesn't scroll; you'll only get the first viewport's worth.
* **Pagination behind a button click.** Reader doesn't click; seed your batch with the individual page URLs directly.
* **Content hidden behind auth.** Reader has no concept of your logged-in session. See [Auth walls](/home/guides/advanced/auth-walls) for options.

## Combining with proxy modes

Sites that hydrate dynamically *and* detect bots are harder still. `waitForSelector` gets you past the hydration; `proxyMode: "premium"` gets you past the bot detection. They work independently, and you might need both:

```ts theme={null}
await reader.read({
  url: "https://shop.example.com/item/42",
  waitForSelector: ".product-price",
  proxyMode: "premium", // residential proxies bypass bot detection
});
```

See [Choosing a proxy mode](/home/guides/advanced/choosing-a-proxy-mode) for when to force a mode explicitly.

## Debugging a timeout

If scrapes with `waitForSelector` consistently fail with `scrape_timeout`:

1. **Test the selector manually.** Open the URL in your browser with devtools, wait for full load, then check whether the selector matches.
2. **Bump `timeoutMs`.** Some sites are slow; 30 seconds may not be enough. Max is 120 seconds.
3. **Try a more general selector.** Maybe your specific class name changed; use something broader.
4. **Check if the page needs premium mode.** Bot-walled pages may never fully hydrate for standard-mode traffic.

## Next

* [Auth walls](/home/guides/advanced/auth-walls)
* [Choosing a proxy mode](/home/guides/advanced/choosing-a-proxy-mode)