> ## Documentation Index
> Fetch the complete documentation index at: https://relevanceai.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Code - JavaScript

> A component to run JavaScript

Although Relevance in general is a zero or low code platform, you can still code your own features using the JavaScript tool step if you want to.

## How to use a JavaScript step

You can add a JavaScript tool-step to any tool by creating a new tool, clicking on the "Add Step" button under the Tool steps sections, searching for "JavaScript" and clicking on the "JavaScript Code" tool step as shown below:

<img src="https://mintcdn.com/relevanceai/c92n16pLC3iTZmPg/images/build-custom-tools/tool-step/js-code-get-started.png?fit=max&auto=format&n=c92n16pLC3iTZmPg&q=85&s=8097bc08d08f7195acee7a94a115f6af" alt="JavaScript step" width="3050" height="1164" data-path="images/build-custom-tools/tool-step/js-code-get-started.png" />

Enter your code in the code section as you do in any other IDE (e.g. VS code, WebStorm)

### Access to input variables, other steps' output and api keys

You can access tool input variables, other tool step outputs, and api\_keys you've created in Relevance using the following syntax:

<img src="https://mintcdn.com/relevanceai/fLFlffrslASJvpw0/images/js-accessing-data.png?fit=max&auto=format&n=fLFlffrslASJvpw0&q=85&s=f94435bd043b69f8580b35dfbf5574af" alt="JavaScript step" width="1000" height="743" data-path="images/js-accessing-data.png" />

* **Access to input variables** is via `params`. `params` is a dictionary and names of variables are the dictionary keys. For example,
  if there is an input parameter named "name" you can access to title value using `params.name`

* **Access to other steps' output** is via `steps`. `steps` is a dictionary and the names of steps are the dictionary keys. For example,
  if there is a step named "summary" you can access its produced value using `steps.summary.output`.
  Or if there is a code step, you can access its produced output using `steps.python.transformed`, where 'python' represents the default variable name for the python code step, which you can change.

* **Access api keys**: You can access api keys you have added to the platform via the integrations page, with `'{{secrets.chains_name_of_your_api_key}}'`.

Note that you can set the output of this step to be a string generated by a Large Language Model (LLM) such as GPT. This can be done
by clicking on the LLM icon on the top right.

### Installing & using packages

### Deno runtime

When using the `Deno` runtime (the default), you can import packages using an `import` expression with a service like `esm.sh`. For example, to use the `change-case` package:

```javascript theme={null}
const { sentenceCase } = await import("https://esm.sh/change-case");

return sentenceCase(title);
```

<Note>Note: you cannot use `import` statements, or `require`.</Note>

```javascript theme={null}
// ❌ don't do these
import { sentenceCase } from 'https://esm.sh/change-case'
import { sentenceCase } from 'change-case'
const { sentenceCase } = require('change-case')
```

#### Node.js runtime

Packages are currently not supported in Node

<Snippet file="components/tools/step-general.mdx" />

## Access the step output

If the name of a JavaScript step is `javascript`, you can access the step output using `javascript.transformed`.
Note that a step name is different from the step title. Step titles can be found on the top left
of steps. A step name is shown on the bottom left, in smaller font and highlighted green.

## Common errors

The most common errors seen in our logs are JavaScript coding related errors to which there are millions of resources available online.
However, occasionally, users encounter the `Code execution timed out` error. Keep in mind that JavaScript snippet execution time
cannot exceed 15 minutes.