JavaScript rendering enables full browser execution to capture dynamically loaded content, handle user interactions, and process JavaScript-heavy websites. Control rendering behavior with advanced options for timeout, iframe handling, and load detection.
When to use Use JavaScript rendering when you need to:
Load dynamic content : Capture content loaded via AJAX or fetch requestsExecute JavaScript : Process sites that require JS for content displayHandle SPAs : Extract data from Single Page Applications (React, Vue, Angular)Wait for interactions : Capture DOM state after user actionsSee final state : Get the page as users see it, not raw HTML
Parameters
Turn JavaScript rendering on or off. When enabled, the page loads in a real browser that executes JavaScript, just like when you visit it yourself. When to enable:
Single Page Applications (React, Vue, Angular)
Content loaded via AJAX or fetch
Sites that need JavaScript to display content
When you need the page as users see it
When to keep disabled (faster, cheaper):
Static HTML pages
Simple websites without JavaScript
When raw HTML is sufficient
Note: Rendering requires vx8 or vx10. The vx6 driver doesn’t support rendering.Example:
Fine-tune how the browser waits and loads the page. Only applies when render: true. Available options:
render_type - When to consider the page “loaded”
load (default) - Wait for the standard page load event - good for most pagesdomready - Stop as soon as HTML is ready, before images load - fastest optionidle2 - Wait until only 2 or fewer network requests in the last 500ms - good for dynamic contentidle0 - Wait until zero network activity for 500ms - most thorough, slowest
timeout - Maximum wait time in milliseconds (default: 30,000)
How long to wait before giving up
include_iframes - Whether to load content inside iframes (default: false)
Enable for embedded videos, widgets, or important iframe content
blocked_domains - List of domains to block during loading
Great for blocking ads, analytics, or tracking scripts
Makes pages load faster and cleaner
Example: "render_options" : { "render_type" : "idle0" , "timeout" : 60000 , "include_iframes" : true , "blocked_domains" : [ "google-analytics.com" , "doubleclick.net" ] }
Usage Enable basic rendering Set render: true to enable JavaScript execution:
from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) result = nimble.extract({ "url" : "https://www.example.com" , "render" : True }) print (result)
When render: false (default), the API returns the raw HTML without JavaScript execution, suitable for static pages.
Advanced JS rendering from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) result = nimble.extract({ "url" : "https://www.example.com" , "render" : True , "render_options" : { "render_type" : "idle0" , "timeout" : 60000 , "include_iframes" : True , "blocked_domains" : [ "ads.example.com" , "tracking.example.com" ] } }) print (result)
Dynamic content loading Wait for AJAX-loaded content:
from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) # Wait for all network activity to stop result = nimble.extract({ "url" : "https://www.example.com/products" , "render" : True , "render_options" : { "render_type" : "idle0" , "timeout" : 45000 } }) print (result[ "data" ][ "html" ])
Single Page Applications Extract from React, Vue, or Angular apps:
from nimble_python import Nimble from pydantic import BaseModel class Product ( BaseModel ): name: str price: float rating: float nimble = Nimble( api_key = "YOUR-API-KEY" ) # SPAs need rendering and proper wait time result = nimble.extract({ "url" : "https://spa-example.com/products" , "render" : True , "render_options" : { "render_type" : "idle2" , "timeout" : 30000 }, "schema" : Product }) print (result[ "data" ])
Include iframe content in extraction:
from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) # Include iframe content (e.g., embedded videos, widgets) result = nimble.extract({ "url" : "https://www.example.com/page-with-iframes" , "render" : True , "render_options" : { "include_iframes" : True , "render_type" : "load" , "timeout" : 40000 }, "formats" : [ "html" ] }) print (result[ "data" ][ "html" ])
Block unnecessary resources Improve performance by blocking ads and tracking:
from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) # Block ads, analytics, and tracking domains result = nimble.extract({ "url" : "https://www.example.com" , "render" : True , "render_options" : { "blocked_domains" : [ "googletagmanager.com" , "google-analytics.com" , "facebook.com" , "doubleclick.net" , "ads.example.com" ], "render_type" : "idle2" , "timeout" : 25000 } }) print (result)
Fast rendering for simple sites Use DOMContentLoaded for faster responses:
from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) # Don't wait for images/styles to load result = nimble.extract({ "url" : "https://www.example.com/article" , "render" : True , "render_options" : { "render_type" : "domready" , "timeout" : 15000 }, "formats" : [ "markdown" ] }) print (result[ "data" ][ "markdown" ])
Combining with browser actions Rendering works seamlessly with browser actions:
from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) # Render page, then perform actions result = nimble.extract({ "url" : "https://www.example.com" , "render" : True , "render_options" : { "render_type" : "idle0" , "timeout" : 30000 }, "browser_actions" : [ { "click" : { "selector" : "button.load-more" , "timeout" : 5000 } }, { "sleep" : "2s" }, { "auto_scroll" : 5000 } ] }) print (result)
Best practices Choose the right render type Use load for standard pages:# ✅ Default for most websites render_options = { "render_type" : "load" }
Use domready for speed:# ✅ When images/styles aren't needed render_options = { "render_type" : "domready" # Faster response }
Use idle2 for dynamic content:# ✅ For AJAX-heavy pages render_options = { "render_type" : "idle2" , # Wait for most requests to finish "timeout" : 30000 }
Use idle0 for complete loading:# ✅ When you need everything loaded render_options = { "render_type" : "idle0" , # Wait for all network activity "timeout" : 60000 # Higher timeout for slow sites }
Optimize timeout settings Set appropriate timeouts: # ❌ Too short - may miss content render_options = { "render_type" : "idle0" , "timeout" : 5000 # Not enough for slow sites } # ✅ Balanced timeout render_options = { "render_type" : "idle0" , "timeout" : 30000 # 30 seconds is usually sufficient } # ✅ Extended for slow sites render_options = { "render_type" : "idle0" , "timeout" : 60000 # Up to 60 seconds for very slow sites }
Block unnecessary domains Common domains to block: common_blocked_domains = [ # Analytics "google-analytics.com" , "googletagmanager.com" , "segment.com" , "mixpanel.com" , # Advertising "doubleclick.net" , "googlesyndication.com" , "adservice.google.com" , # Social media widgets "facebook.com" , "twitter.com" , "linkedin.com" , # CDN for ads "ads.example.com" , "tracking.example.com" ] result = nimble.extract({ "url" : "https://www.example.com" , "render" : True , "render_options" : { "blocked_domains" : common_blocked_domains } })
Benefits of blocking:
Faster page loads
Lower bandwidth usage
Reduced detection risk
Cleaner HTML output
Handle iframes carefully Enable only when needed: # ❌ Don't enable iframes unnecessarily render_options = { "include_iframes" : True # Slower and larger response } # ✅ Enable only for specific content if need_iframe_content: render_options = { "include_iframes" : True , "timeout" : 45000 # Increase timeout for iframes } else : render_options = { "include_iframes" : False }
Combine with network capture Monitor and capture API calls during rendering:
from nimble_python import Nimble nimble = Nimble( api_key = "YOUR-API-KEY" ) # Render page and capture specific API calls result = nimble.extract({ "url" : "https://www.example.com" , "render" : True , "render_options" : { "render_type" : "idle0" , "timeout" : 30000 }, "network_capture" : [ { "method" : "GET" , "url" : { "type" : "contains" , "value" : "/api/products" } } ] }) # Access captured network data api_responses = result[ "data" ][ "network_capture" ] print (api_responses)
Choose the minimal driver: # ❌ Don't use vx10 when vx8 works result = nimble.extract({ "url" : "https://simple-spa.com" , "driver" : "vx10" , # Unnecessary stealth features "render" : True }) # ✅ Use appropriate driver result = nimble.extract({ "url" : "https://simple-spa.com" , "driver" : "vx8" , # Sufficient for most SPAs "render" : True })
Monitor execution time: result = nimble.extract({ "url" : "https://www.example.com" , "render" : True }) # Check rendering performance exec_time = result[ "metadata" ][ "execution_time_ms" ] print ( f "Rendering took { exec_time } ms" ) # Optimize if too slow if exec_time > 10000 : print ( "Consider blocking domains or changing render_type" )
When to skip rendering Use non-rendering (vx6) when:
Static content : HTML already contains all dataAPI endpoints : Fetching JSON directlyHigh throughput needed : Rendering is slowerSimple pages : No JavaScript requiredCost optimization : Non-rendering is cheaper
# ✅ Skip rendering for static pages result = nimble.extract({ "url" : "https://static-site.com/page.html" , "render" : False , # or omit (false is default) })
