Running Node.js in workflows

Pipedream supports writing Node.js v20 at any point of a workflow.

Anything you can do with Node.js, you can do in a workflow. This includes using most ofnpm’s 400,000+ packages. JavaScript is one of themost usedlanguages in the world, with a thriving community and extensive package ecosystem. If you work on websites and know JavaScript well, Pipedream makes you a full stack engineer. If you’ve never used JavaScript, see theresources below.

Adding a code step

1. Click the+ button below any step of your workflow.
2. Select the option toRun custom code.

Note that new code steps will default to Node.js v20. You can add any Node.js code in the editor that appears. For example, try:

export default defineComponent({  async run({steps,$ }) {    console.log("This is Node.js code");    $.export("test","Some test data");    return "Test data";  },});

Code steps use the same editor (Monaco) used in Microsoft’sVS Code, which supports syntax highlighting, automatic indentation, and more.

Sharing data between steps

A Node.js step can use data from other steps usingstep exports, it can also export data for other steps to use.

Using data from another step

In Node.js steps, data from the initial workflow trigger and other steps are available in thesteps argument passed to therun({ steps, $ }) function.

In this example, we’ll pretend this data is coming into our HTTP trigger via POST request.

{  "id":1,  "name":"Bulbasaur",  "type":"plant"}

In our Node.js step, we can access this data in thesteps variable Specifically, this data from the POST request into our workflow is available in thetrigger property.

export default defineComponent({  async run({steps,$ }) {    const pokemonName = steps.trigger.event.name;    const pokemonType = steps.trigger.event.type;    console.log(`${pokemonName} is a ${pokemonType} type Pokemon`);  },});

Sending data downstream to other steps

To share data created, retrieved, transformed or manipulated by a step to others downstream you can simplyreturn it.

// This step is named "code" in the workflowimport axiosfrom "axios";export default defineComponent({  async run({steps,$ }) {    const response = await axios.get(      "https://pokeapi.co/api/v2/pokemon/charizard"    );    // Store the response's JSON contents into a variable called "pokemon"    const pokemon = response.data;    // Expose the pokemon data downstream to other steps in the $return_value from this step    return pokemon;  },});

Using $.export

Alternatively, use the built in$.export helper instead of returning data. The$.export creates anamed export with the given value.

// This step is named "code" in the workflowimport axiosfrom "axios";export default defineComponent({  async run({steps,$ }) {    const response = await axios.get(      "https://pokeapi.co/api/v2/pokemon/charizard"    );    // Store the response's JSON contents into a variable called "pokemon"    const pokemon = response.data;    // Expose the pokemon data downstream to other steps in the pokemon export from this step    $.export("pokemon", pokemon);  },});

Now thispokemon data is accessible to downstream steps withinsteps.code.pokemon

Passing props to code steps

You can make code steps reusable by allowing them to accept props. Instead of hard-coding the values of variables within the code itself, you can pass them to the code step as arguments or parametersentered in the workflow builder.

For example, let’s define afirstName prop. This will allow us to freely enter text from the workflow builder.

export default defineComponent({  props: {    firstName: {      type:"string",      label:"Your first name",      default:"Dylan",    },  },  async run({steps,$ }) {    console.log(      `Hello ${this.firstName}, congrats on crafting your first prop!`    );  },});

The workflow builder now can accept text input to populate thefirstName to this particular step only:

Accepting a single string is just one example, you can build a step to accept arrays of strings through a dropdown presented in the workflow builder.

Read the props reference for the full list of options.

How Pipedream Node.js components work

When you add a new Node.js code step or use the examples in this doc, you’ll notice a common structure to the code:

export default defineComponent({  async run({steps,$ }) {    // this Node.js code will execute when the step runs  },});

This definesa Node.js component. Components let you:

• Pass input to steps usingprops
• Connect an account to a step
• Issue HTTP responses
• Perform workflow-level flow control, likeending a workflow early

When the step runs, Pipedream executes therun method:

• Any asynchronous code within a code stepmust be run synchronously, using theawait keyword or with a Promise chain, using.then(),.catch(), and related methods.
• Pipedream passes thesteps variable to the run method.steps is also an object, and contains thedata exported from previous steps in your workflow.
• You also have access to the$ variable, which gives you access to methods like$.respond,$.export,and more.

If you’re usingprops orconnect an account to a step, the component exposes them in the variablethis, which refers to the current step:

export default defineComponent({  async run({steps,$ }) {    // `this` refers to the running component. Props, connected accounts, etc. are exposed here    console.log(this);  },});

When youconnect an account to a step, Pipedream exposes the auth info in the variablethis.appName.$auth.

Logs

You can callconsole.log orconsole.error to add logs to the execution of a code step.

These logs will appear just below the associated step.console.log messages appear in black,console.error in red.

console.dir

If you need to print the contents of JavaScript objects, useconsole.dir:

export default defineComponent({  async run({steps,$ }) {    console.dir({      name:"Luke",    });  },});

Syntax errors

Pipedream will attempt to catch syntax errors when you’re writing code, highlighting the lines where the error occurred in red.

Usingnpm packages

npm hosts JavaScript packages: libraries of code someone else wrote and packaged for others to use. npm has over 400,000 packages and counting.

Justimport it

To use an npm package on Pipedream, simplyimport it:

import axiosfrom "axios";

By default, workflows don’t have any packages installed. Just import any package in this manner to make it available in the step.

If a package only supports theCommonJS module format, you may have torequire it:

const axios = require("axios");

Within a single step, you can only useimport orrequire statements, not both. Seethis section for more details.

When Pipedream runs your workflow, we download the associated npm package for you before running your code steps.

If you’ve used Node before, you’ll notice there’s nopackage.json file to upload or edit. We want to make package management simple, so justimport orrequire the module like you would in your code, after package installation, and get to work.

Third-party package limitations

Some packages require access to a web browser to run, and don’t work with Node.js. Often this limitation is documented on the packageREADME, but often it’s not. If you’re not sure and need to use it, we recommend just trying toimport orrequire it.

Other packages require access to binaries or system libraries that aren’t installed in the Pipedream execution environment.

If you’re seeing any issues with a specific package, pleaselet us know and we’ll try to help you make it work.

Pinning package versions

Each time you deploy a workflow with Node.js code, Pipedream downloads the npm packages youimport in your step.By default, Pipedream deploys the latest version of the npm package each time you deploy a change.

There are many cases where you may want to specify the version of the packages you’re using. If you’d like to use aspecific version of a package in a workflow, you can add that version in theimport string, for example:

import axiosfrom "axios@0.19.2";

You can also pass the version specifiers used by npm to supportsemantic version upgrades. For example, to allow for future patch version upgrades:

import axiosfrom "axios@~0.20.0";

To allow for patch and minor version upgrades, use:

import gotfrom "got@^11.0.0";

You can also specify different versions of the same package in different steps. Each step will used the associated version. Note that this also increases the size of your deployment, which can affect cold start times.

CommonJS vs. ESM imports

In Node.js, you may be used to importing third-party packages using therequire statement:

const axios = require("axios");

In this example, we’re including theaxiosCommonJS module published to npm. You import CommonJS modules using therequire statement.

But you may encounter this error in workflows:

Error Must use import to load ES Module

This means that the package you’re trying torequire uses a different format to export their code, calledECMAScript modules (ESM, orES modules, for short). With ES modules, you instead need toimport the package:

import gotfrom "got";

Most package publish both CommonJS and ESM versions, soif you always useimport, you’re less likely to have problems. In general, refer to the documentation for your package for instructions on importing it correctly.

require is not defined

This error means that you cannot use CommonJS and ESM imports in the same step. For example, if you run code like this:

import fetchfrom "node-fetch";const axios = require("axios");

your workflow will throw arequire is not defined error. There are two solutions:

1. Try converting your CommonJSrequire statement into an ESMimport statement. For example, convert this:

const axios = require("axios");

to this:

import axiosfrom "axios";

2. If theimport syntax fails to work, separate your imports into different steps, using only CommonJS requires in one step, and only ESM imports in another.

Variable scope

Any variables you create within a step are scoped to that step. That is, they cannot be referenced in any other step.

Within a step, thenormal rules of JavaScript variable scope apply.

When you need to share data across steps, usestep exports.

Making HTTP requests from your workflow

There are two ways to make HTTP requests in code steps:

• Use any HTTP client that works with Node.js.See this example guide for how to useaxios to make HTTP requests.
• Use$.send.http(), a Pipedream-provided method for making asynchronous HTTP requests.

In general, if you just need to make an HTTP request but don’t care about the response,use$.send.http(). If you need to operate on the data in the HTTP response in the rest of your workflow,useaxios.

Returning HTTP responses

You can return HTTP responses fromHTTP-triggered workflows using the$.respond() function.

Invoke another workflow

You can invoke another workflow in your workspace with$.flow.trigger:

await $.flow.trigger(  workflowId, // your Pipedream workflow ID, e.g. p_abc123  payload, // any JSON-serializable data)

Find your workflow’s ID here.

This invokes the workflow directly — you don’t need to configure a trigger, and the request does not leave the platform.

We also provide aTrigger Workflow action in theHelper Functions app so you don’t need to do it by code!

Ending a workflow early

Sometimes you want to end your workflow early, or otherwise stop or cancel the execution or a workflow under certain conditions. For example:

• You may want to end your workflow early if you don’t receive all the fields you expect in the event data.
• You only want to run your workflow for 5% of all events sent from your source.
• You only want to run your workflow for users in the United States. If you receive a request from outside the U.S., you don’t want the rest of the code in your workflow to run.
• You may use theuser_id contained in the event to look up information in an external API. If you can’t find data in the API tied to that user, you don’t want to proceed.

In any code step, callingreturn $.flow.exit() will end the execution of the workflow immediately. No remaining code in that step, and no code or destination steps below, will run for the current event.

export default defineComponent({  async run({steps,$ }) {    return $.flow.exit();    console.log(      "This code will not run, since $.flow.exit() was called above it"    );  },});

You can pass any string as an argument to$.flow.exit():

export default defineComponent({  async run({steps,$ }) {    return $.flow.exit("End message");  },});

Or exit the workflow early within a conditional:

export default defineComponent({  async run({steps,$ }) {    // Flip a coin, running $.flow.exit() for 50% of events    if (Math.random()> 0.5) {      return $.flow.exit();    }    console.log("This code will only run 50% of the time");  },});

Errors

Errors raised in a code step will stop the execution of code or destinations that follow.

Configuration Error

Throwing aConfigurationError in a Node.js step will display the error message in a dedicated area.

This is useful for providing feedback during validation ofprops. In the example below, a required Header value is missing from the Google Sheets action:

Or you can use it for validating the format of a givenemail prop:

import { ConfigurationError }from "@pipedream/platform";export default defineComponent({  props: {    email: { type:"string" },  },  async run({steps,$ }) {    // if the email address doesn't include a @, it's not valid    if (!this.email.includes("@")) {      throw new ConfigurationError("Provide a valid email address");    }  },});

Using secrets in code

Workflow code is private. Still, we recommend you don’t include secrets — API keys, tokens, or other sensitive values — directly in code steps.

Pipedream supportsenvironment variables for keeping secrets separate from code. Once you create an environment variable in Pipedream, you can reference it in any workflow usingprocess.env.VARIABLE_NAME. The values of environment variables are private.

See theEnvironment Variables docs for more information.

Limitations of code steps

Code steps operate within thegeneral constraints on workflows. As long as you stay within those limits and abide by ouracceptable use policy, you can add any number of code steps in a workflow to do virtually anything you’d be able to do in Node.js.

If you’re trying to run code that doesn’t work or you have questions about any limits on code steps,please reach out.

Editor settings

We use theMonaco Editor, which powers VS Code and other web-based editors.

We also let you customize the editor. For example, you can enable Vim mode, and change the default tab size for indented code. Visit yourSettings to modify these settings.

Keyboard Shortcuts

We use theMonaco Editor, which powers VS Code. As a result, many of the VS Codekeyboard shortcuts should work in the context of the editor.

For example, you can use shortcuts to search for text, format code, and more.

New to JavaScript?

We understand many of you might be new to JavaScript, and provide resources for you to learn the language below.

When you’re searching for how to do something in JavaScript, some of the code you try might not work in Pipedream. This could be because the code expects to run in a browser, not a Node.js environment. The same goes fornpm packages.

I’m new to programming

Many of the most basic JavaScript tutorials are geared towards writing code for a web browser to run. This is great for learning — a webpage is one of the coolest things you can build with code. We recommend starting with these general JavaScript tutorials and trying the code you learn on Pipedream:

• JavaScript For Cats
• Mozilla - JavaScript First Steps
• StackOverflow operates a programming Q&A site that typically has the first Google result when you’re searching for something specific. It’s a great place to find answers to common questions.

I know how to code, but don’t know JavaScript

• A re-introduction to JavaScript (JS tutorial)
• MDN language overview
• Eloquent Javascript
• Node School
• You Don’t Know JS