Execute Javascript code

Run JS code with access to variables of current state

This transformation is able to execute Javascript code and return a variable as output. It runs in an isolated environment with the state of the chain passed in as variables that can be accessed via steps and params like any other variable. The code must return a value that is then used as the output of the transformation, if no return is provided then there will be no output.

For example, if you wanted to set a default value for a input parameter you would do it as so:

return {
  selected_language: params.selected_language ?? 'en'

Or if you wanted to check two values from different steps and only return the highest:

let highestValue = steps.first_value.output.answer;

if (highestValue < steps.second_value.output.answer) {
  highestValue = steps.second_value.output.answer;

return highestValue;


Don't forget to return a value

If the code doesn't return any value, it will not have an output. console.log is ignored.

Screenshot of the JS code transformation in the Relevance AI Notebook

Screenshot of the JS code transformation in the Notebook

Common errors

  • No return is provided in the code
  • Execution time exceeds 10 seconds
  • An error in the code



CodeThe JavaScript code to executeStringβœ…


TransformedThe returned value from the codeString
durationThe duration of code execution in millisecondsNumber