Custom Code Steps

How to write and execute custom JavaScript code as test steps — for complex logic, calculations, and DOM interactions that go beyond natural language steps.

Who is this for? SDETs and developers who need to execute custom JavaScript within a test case for logic that cannot be expressed as a natural language step.

Custom code steps let you write JavaScript that executes during test runtime. Use them for complex calculations, custom data transformations, direct DOM manipulation, or any scenario where a natural language instruction is insufficient.

Prerequisites

• You have created or opened a test case.

• You are familiar with the Test Steps Editor basics.

• You have working knowledge of JavaScript.

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Adding a custom code step

1. Open a test case and click Add Step.

2. In the step builder sidebar, select Custom Code.

3. Select JavaScript from the Language dropdown.

4. Write your code in the code editor.

5. Click Create Step to add the step to your test case.

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Fields

Field	Description
Language	The scripting language. Currently supports JavaScript.
Code	The JavaScript code to execute at runtime.
Description	A plain-English summary of what the code does. Appears in the step list and execution report.
Metadata	Optional metadata string stored with the step. Useful for tagging or categorizing custom code steps.

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Example: Generate a unique identifier

// Generate a unique email for registration testing
const timestamp = Date.now();
const uniqueEmail = `testuser_${timestamp}@example.com`;
return uniqueEmail;

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Example: Calculate and verify a total

// Calculate expected cart total from individual prices
const prices = [19.99, 24.50, 7.99];
const expectedTotal = prices.reduce((sum, price) => sum + price, 0).toFixed(2);
return expectedTotal;
// => "52.48"

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Example: Parse and transform data

// Extract order IDs from a JSON response stored in a variable
const response = JSON.parse(context.variables.orderListResponse);
const orderIds = response.body.orders.map(order => order.id);
return orderIds.join(', ');

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Advanced settings

Setting	Description
Skip Step	Skip this step during execution without removing it from the test case.
Mark as Optional	If enabled, a failure on this step does not fail the overall test case.

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Tips & best practices

• Add a descriptive Description field so the step is understandable in the execution report without reading the code.

• Keep code minimal. Custom code steps are for logic that natural language steps cannot handle. If a task can be described in plain English, use an AI Agent step instead.

• Use custom code for data transformation between steps — formatting dates, calculating expected values, parsing complex response structures.

• Avoid long-running operations. The step has a default timeout of 30 seconds. If your code needs more time, increase the step timeout.

Troubleshooting

Custom code step fails with a syntax error Check the browser console output in the execution report. JavaScript syntax errors surface as step failures with the error message in the step details. Validate your code in a browser console before pasting it into the step editor.

Variables from previous steps are not accessible Verify the variable name is spelled correctly and that the step that sets the variable runs before the custom code step. Variable names are case-sensitive.

Related pages

• Test Steps Editor

• Test Data Management

• Creating Test Cases

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