Scrape JavaScript-rendered pages

Many pages ship an empty shell and fill it with JavaScript after load. Send them to Fetch with js_render=true and wait_for set to the element you need, and you get the HTML after the content has arrived. Uses: Fetch with js_render, wait_for, wait and block_resources

Ask your AI agent

With the Zenrows MCP server connected to Claude, Cursor or any MCP client, paste this prompt. Your agent picks the right Zenrows tools and settings on its own.

Use Zenrows to read https://www.scrapingcourse.com/javascript-rendering after the products
have loaded, and list every product name with its price.

Render the page and wait for the content

The product grid on this page is filled by a background call after the page loads. js_render=true runs the page in a browser, and wait_for=.product-name holds the capture until the first product name is in the DOM. css_extractor then returns only the names and prices as JSON.

import json
import requests

params = {
    "apikey": "YOUR_ZENROWS_API_KEY",
    "url": "https://www.scrapingcourse.com/javascript-rendering",
    "js_render": "true",
    "wait_for": ".product-name",
    "css_extractor": json.dumps({"names": ".product-name", "prices": ".product-price"}),
}

response = requests.get("https://api.zenrows.com/v1/", params=params, timeout=180)
response.raise_for_status()

data = response.json()
for name, price in list(zip(data["names"], data["prices"]))[:5]:
    print(f"{name}: {price}")
print("Credits billed:", response.headers["X-Request-Credits"])

const params = new URLSearchParams({
  apikey: "YOUR_ZENROWS_API_KEY",
  url: "https://www.scrapingcourse.com/javascript-rendering",
  js_render: "true",
  wait_for: ".product-name",
  css_extractor: JSON.stringify({ names: ".product-name", prices: ".product-price" }),
});

const response = await fetch(`https://api.zenrows.com/v1/?${params}`, {
  signal: AbortSignal.timeout(180_000),
});
if (!response.ok) throw new Error(`${response.status}: ${await response.text()}`);

const data = await response.json();
data.names.slice(0, 5).forEach((name, i) => console.log(`${name}: ${data.prices[i]}`));
console.log("Credits billed:", response.headers.get("X-Request-Credits"));

curl "https://api.zenrows.com/v1/?apikey=YOUR_ZENROWS_API_KEY&url=https%3A%2F%2Fwww.scrapingcourse.com%2Fjavascript-rendering&js_render=true&wait_for=.product-name&css_extractor=%7B%22names%22%3A%22.product-name%22%2C%22prices%22%3A%22.product-price%22%7D"

Drop css_extractor to get the full rendered HTML instead. From the CLI, the same render and wait print the rendered products as markdown. --wait-for runs in manual mode with --js-render:

CLI

zenrows fetch https://www.scrapingcourse.com/javascript-rendering --manual --js-render --wait-for .product-name --output markdown

Example output

Chaz Kangeroo Hoodie: $52
Teton Pullover Hoodie: $70
Bruno Compete Hoodie: $63
Frankie  Sweatshirt: $60
Hollister Backyard Sweatshirt: $52
Credits billed: 5

Wait a fixed time instead

When there is no single element to wait for, for example a chart that animates in, add wait in milliseconds. Zenrows waits that long after the page loads before capturing it.

Python (Requests)

import json
import requests

params = {
    "apikey": "YOUR_ZENROWS_API_KEY",
    "url": "https://www.scrapingcourse.com/javascript-rendering",
    "js_render": "true",
    "wait": "3000",
    "css_extractor": json.dumps({"names": ".product-name"}),
}

response = requests.get("https://api.zenrows.com/v1/", params=params, timeout=180)
response.raise_for_status()
print(len(response.json()["names"]), "products")

Output: 12 products. Prefer wait_for when you can name an element: it returns as soon as the element appears, while wait always spends the full time.

Block resources to render faster

Images, fonts and stylesheets rarely matter for data. block_resources skips them during the render, which makes the page load faster. Keep script, xhr and fetch unblocked when the content arrives through JavaScript.

Python (Requests)

import json
import requests

params = {
    "apikey": "YOUR_ZENROWS_API_KEY",
    "url": "https://www.scrapingcourse.com/javascript-rendering",
    "js_render": "true",
    "wait_for": ".product-name",
    "block_resources": "image,media,font,stylesheet",
    "css_extractor": json.dumps({"names": ".product-name"}),
}

response = requests.get("https://api.zenrows.com/v1/", params=params, timeout=180)
response.raise_for_status()
print(len(response.json()["names"]), "products")

Output: 12 products, the same data with fewer downloads.

Customize it

Change	How
Let Zenrows decide when to render	Use `mode=auto`, see Adaptive Stealth Mode. Switch to `js_render` with `wait_for` when you need to time the capture
Protected site that also renders with JavaScript	Add `premium_proxy=true`, see Scrape pages protected by anti-bot systems
Click “Load more” or scroll first	Add `js_instructions`, see Click, fill, and scroll before you scrape
Read the JSON the page loads in the background	Add `json_response=true`, see Capture the network requests behind a page
Markdown for an LLM	Add `response_type=markdown`, see Turn any web page into LLM-ready markdown

Troubleshooting

The response comes back but the data is empty: the capture happened before the content loaded. Add wait_for with a selector that appears once the content is in, like .product-name here.
422 after adding wait_for: the selector never appeared. Open the page in your browser, inspect the element and copy a selector from the rendered DOM, not from the page source. See Wait for selector.
mode=auto returns the page before the late content loads: the page answered fast on its first try. Use js_render=true with wait_for for that page, so the capture waits for the content.
Part of the page is missing with block_resources: a blocked resource type carries the content. Remove xhr, fetch or script from the list.
wait or wait_for has no effect: both apply to rendered requests. Add js_render=true to the same request.

Click, fill, and scroll before you scrape

Load more items, scroll a feed or submit a search first.

Capture the network requests behind a page

Read the JSON behind the page instead of its HTML.

Scrape pages protected by anti-bot systems

Let Adaptive Stealth Mode pick the right configuration per page.

Capture screenshots, PDFs, and files

Save the rendered page as an image or a PDF.

Start Here

Foundations Course

Fetch Recipes

Extract Recipes

Crawl Recipes

Batch Recipes

Browser Recipes

Pipelines

Use Cases

By Surface

Production

Scrape JavaScript-rendered pages

Ask your AI agent

Render the page and wait for the content

Example output

Wait a fixed time instead

Block resources to render faster

Customize it

Troubleshooting

Click, fill, and scroll before you scrape

Capture the network requests behind a page

Scrape pages protected by anti-bot systems

Capture screenshots, PDFs, and files

​Ask your AI agent

​Render the page and wait for the content

​Example output

​Wait a fixed time instead

​Block resources to render faster

​Customize it

​Troubleshooting

​Related recipes

Click, fill, and scroll before you scrape

Capture the network requests behind a page

Scrape pages protected by anti-bot systems

Capture screenshots, PDFs, and files

Ask your AI agent

Render the page and wait for the content

Example output

Wait a fixed time instead

Block resources to render faster

Customize it

Troubleshooting

Related recipes