Execute JavaScript

Executes JavaScript code in the current frame or window of the selected WebDriver. Data can be transferred between KNIME and the JavaScript code, by specifying a return type for the executed code and/or selecting input columns which provide argument values for the executed code.

Arguments can be accessed within JavaScript code through the arguments array. The following argument and return data types are supported:

JavaScript	KNIME Cell	KNIME Flow Variable
HTML Element	WebElement	—
Decimal Number	Double	Double
Non-decimal Number	Long	Long, Int
Boolean	Boolean	Boolean
String	String	String
Array	List, JSON	Double, Long, Int, Boolean, String Array
Object	JSON	—

The following snippet will return a JSON object which is mapped to a JSON cell in KNIME. For this, set the “Return type” to “JSON”:

const result = { property1: 'a', property2: 2, property3: [ 'b', 'c', 'c' ] };
return result;

In case you need to execute code asynchronously, enable the [asyncCallbackMethod] argument. In this case, the last argument given to the executed code is the callback which signals that the code has finished execution. In case you need to return results from your asynchronous code, provide it as argument to the callback method. For example, the following JavaScript code causes the browser to sleep for five seconds, then the execution continues:

const callback = arguments[arguments.length - 1]; // last argument is callback
window.setTimeout(function() {
  console.log('finished');
  callback(); // invoke the callback to continue execution
}, 5000);
        

Timeouts for asynchronous execution can be configured in the Start WebDriver node in the “Timeouts” tab: Script timeout.