Javascript Scenario

Scrapfly's js_scenario provides an ability to fully control a headless web browser. Javascript Scenario can be used to issue browser commands like clicking buttons, filling in forms, scrolling and executing custom javascript code.

This feature require Javascript Rendering enabled and the target page must be an html page, otherwise it's not executed.

Javascript scenario details are available in the API response result.browser_data.js_scenario as well as the monitoring dashboard:

javascript scenario view on monitoring dashboard


Javascript scenario consists of one or multiple browser actions that are passed to Scrapfly as a base64 encoded JSON array. An average scenario looks something like this:

Each scenario step is a JSON object with a single key that represents the action to be performed and details of the action.

Once you design your javascript scenario use Scrapfly's base64 encoding online tool to convert it to a base64 encoded string that can be passed to the API for execution.

Note on Timeouts

The entire Javascript Scenario has an execution budget of 25 seconds. Scrapfly does a rough estimation on the maximum JS scenario execution time and will reject any scenarios that are estimated to take more than 25 seconds.

For long-running javascript scenario requiring more than 25sec - You can check the how timeout works
TL;DR retry=false timeout after 90s by default and you can customize the timeout with retry=false&timeout=120000

Full example with API Player

The best way to get familiar with Javascript Scenarios is to use the Scrapfly Web Player to design and test your scenario. However, here's an example to get you started - this scenario will login to by performing these steps:

  • Select username input box and fill value user123
  • Select password input box and fill value password
  • Select and click login button
  • Wait for navigation to acknowledge button click for maximum of 5 seconds

Then, this scenario can be base64 encoded and passed to Scrapfly API for execution:

curl -G \
--request "GET" \
--url "" \
--data-urlencode "render_js=true" \
--data-urlencode "js_scenario=W3siZmlsbCI6eyJzZWxlY3RvciI6ImlucHV0W25hbWU9dXNlcm5hbWVdIiwidmFsdWUiOiJ1c2VyMTIzIn19LHsiZmlsbCI6eyJzZWxlY3RvciI6ImlucHV0W25hbWU9cGFzc3dvcmRdIiwidmFsdWUiOiJwYXNzd29yZCJ9fSx7ImNsaWNrIjp7InNlbGVjdG9yIjoiYnV0dG9uW3R5cGU9J3N1Ym1pdCddIn19LHsid2FpdF9mb3JfbmF2aWdhdGlvbiI6eyJ0aW1lb3V0Ijo1MDAwfX1d" \
--data-urlencode "key=__API_KEY__" \
--data-urlencode "url="


render_js    = "true" 
js_scenario  = "W3siZmlsbCI6eyJzZWxlY3RvciI6ImlucHV0W25hbWU9dXNlcm5hbWVdIiwidmFsdWUiOiJ1c2VyMTIzIn19LHsiZmlsbCI6eyJzZWxlY3RvciI6ImlucHV0W25hbWU9cGFzc3dvcmRdIiwidmFsdWUiOiJwYXNzd29yZCJ9fSx7ImNsaWNrIjp7InNlbGVjdG9yIjoiYnV0dG9uW3R5cGU9J3N1Ym1pdCddIn19LHsid2FpdF9mb3JfbmF2aWdhdGlvbiI6eyJ0aW1lb3V0Ijo1MDAwfX1d" 
key          = "" 
url          = "" 

Example of response with scenario

Scenario Step Types

Currently, 7 scenario types are supported. Each scenario type has a different set of mandatory and optional parameters.

  • [MANDATORY] param_name:type
  • [OPTIONAL] param_name:type


selector:string ignore_if_not_visible:bool=false timeout budget (ms): +2500

Click on a visible element. It's a native click and emit a trusted event - it's not simulated with javascript.

Internal Workflow

  • Waiting element to be visible
  • Moving to the element (mouse and scroll) like a human
  • Trigger the focus of the element
  • Left click


  • selector:string Accept CSS Selector and XPATH Selector
  • ignore_if_not_visible:bool Wait the element if visible then just skip if not
  • multiple:bool If multiple element match, click on all matched elements



selector:string value:string timeout budget (ms): +${timeout} +500

Type the provided value in the targeted element. The typing is not simulated in javascript - it's from real keyboard input.

Internal Workflow

  • Waiting element to be visible
  • Moving to the element (mouse and scroll) like a human
  • Trigger the focus of the element
  • Type the value in the input like a human


  • selector:string Any valid CSS and XPATH Selector
  • value:string Value to type in element
  • clear:boolean Clear the input field before writing



Condition are exclusive to one of

  • status_code:int
  • selector:string
    • selector_state:string=existing
    • timeout:int=1000


  • selector:string Any valid CSS or XPATH selector
  • selector_state:string Can be existing or not_existing
  • action:string Action when the condition is met, can be continue, exit_success, exit_failed

Play the scenario only if the condition is met

Internal Workflow

  • Check the equality of the status code with the response status code



timeout budget (ms): +${wait}

Make a pause during the scenario. The whole pause time is added to the scenario budget


There is no parameter, you pass directly the value expressed in millisecond



element:string=body selector:string=bottom timeout budget (ms): +500

Scroll to the selector (if no selector, scroll to the bottom). If the element parameter is a valid selector, it's scroll within the element. The scroll is not simulated with javascript - it's simulated with real mouse input.

Internal Workflow

  • Wait the element is visible
  • Wait the selector is visible
  • Scroll like a human


  • element:string=body a valid css selector or xpath or "body"
  • selector:string a valid css selector or xpath or "bottom"
  • infinite:int=0 infinite scroll - number of scroll iteration



timeout:int=3000 timeout budget (ms): +${timeout}

Execute a javascript script and store the result if a result is returned

Internal Workflow

  • The Javascript code is executed
  • If the javascript code return something - it's stored and available in API response result.browser_data.js_scenario.steps, all "execute" step have a result entry.
  • Support Async/Await function


  • script:string Script to execute, it can return serializable value
  • timeout:int Timeout to wait after the script execution have started - expressed in millisecond


Wait For Navigation

timeout:int=1000 timeout budget (ms): +${timeout} + 1500

Time to wait to detect a navigation / changing page. The given timeout + 1500 (1.5s) is added to the scenario budget - this additional time represent the average duration of a standard page loading (with assets, xhr, etc). For example if you set a timeout of 1000, 2500 is counted.


  • timeout:int Maximum timeout to wait for a navigation - expressed in millisecond


Wait For Selector

selector:string=body state:string=visible timeout budget (ms): +${timeout}

Wait the element is visible (if state=visible) in the page or the element disappear (state=hidden). If the selector is not present in the desired state until the timeout this step failed and the scenario is aborted. The timeout is added to the scenario budget


  • selector:string=body a valid css selector or xpath or "body"
  • state:string=visible state of the element in the page "visible" or "hidden"
  • timeout:int=5000 Timeout to wait before fail - expressed in milliseconds