Client Library for JavaScript / TypeScript

Introduction

The client for JavaScript / TypeScript provides a seamless interface to interact with fal.

Installation

First, add the client as a dependency in your project:

npm install --save @fal-ai/serverless-client

Features

1. Call an endpoint

Endpoints requests are managed by a queue system. This allows fal to provide a reliable and scalable service.

The subscribe method allows you to submit a request to the queue and wait for the result.

import * as fal from "@fal-ai/serverless-client";
 
const result = await fal.subscribe("fal-ai/flux/dev", {
  input: {
    prompt: "a cat",
    seed: 6252023,
    image_size: "landscape_4_3",
    num_images: 4,
  },
  logs: true,
  onQueueUpdate: (update) => {
    if (update.status === "IN_PROGRESS") {
      update.logs.map((log) => log.message).forEach(console.log);
    }
  },
});

2. Queue Management

You can manage the queue using the following methods:

Submit a Request

Submit a request to the queue using the queue.submit method.

import * as fal from "@fal-ai/serverless-client";
 
const { request_id } = await fal.queue.submit("fal-ai/flux/dev", {
  input: {
    prompt: "a cat",
    seed: 6252023,
    image_size: "landscape_4_3",
    num_images: 4,
  },
  webhookUrl: "https://optional.webhook.url/for/results",
});

This is useful when you want to submit a request to the queue and retrieve the result later. You can save the request_id and use it to retrieve the result later.

Webhooks

For long-running requests, such as training jobs, you can use webhooks to receive the result asynchronously. You can specify the webhook URL when submitting a request.

Check Request Status

Retrieve the status of a specific request in the queue:

import * as fal from "@fal-ai/serverless-client";
 
const status = await fal.queue.status("fal-ai/flux/dev", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
  logs: true,
});

Retrieve Request Result

Get the result of a specific request from the queue:

import * as fal from "@fal-ai/serverless-client";
 
const result = await fal.queue.result("fal-ai/flux/dev", {
  requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
});

3. File Uploads

Some endpoints require files as input. However, since the endpoints run asynchronously, processed by the queue, you will need to provide URLs to the files instead of the actual file content.

Luckily, the client library provides a way to upload files to the server and get a URL to use in the request.

import * as fal from "@fal-ai/serverless-client";
 
const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);

4. Streaming

Some endpoints support streaming:

import * as fal from "@fal-ai/serverless-client";
 
const stream = await fal.stream("fal-ai/flux/dev", {
  input: {
    prompt: "a cat",
    seed: 6252023,
    image_size: "landscape_4_3",
    num_images: 4,
  },
});
 
for await (const event of stream) {
  console.log(event);
}
 
const result = await stream.done();

5. Realtime Communication

For the endpoints that support real-time inference via WebSockets, you can use the realtime client that abstracts the WebSocket connection, re-connection, serialization, and provides a simple interface to interact with the endpoint:

import * as fal from "@fal-ai/serverless-client";
 
const connection = fal.realtime.connect("fal-ai/flux/dev", {
  onResult: (result) => {
    console.log(result);
  },
  onError: (error) => {
    console.error(error);
  },
});
 
connection.send({
  prompt: "a cat",
  seed: 6252023,
  image_size: "landscape_4_3",
  num_images: 4,
});

6. Run

The endpoints can also be called directly instead of using the queue system.

Prefer the queue

We do not recommend this use most use cases as it will block the client until the response is received. Moreover, if the connection is closed before the response is received, the request will be lost.

import * as fal from "@fal-ai/serverless-client";
 
const result = await fal.run("fal-ai/flux/dev", {
  input: {
    prompt: "a cat",
    seed: 6252023,
    image_size: "landscape_4_3",
    num_images: 4,
  },
});

API Reference

For a complete list of available methods and their parameters, please refer to JavaScript / TypeScript API Reference documentation (opens in a new tab).

Examples

Check out some of the examples below to see real-world use cases of the client library:

See fal.realtime in action with SDXL Lightning: https://github.com/fal-ai/sdxl-lightning-demo-app (opens in a new tab)

Support

If you encounter any issues or have questions, please visit the GitHub repository (opens in a new tab) or join our Discord Community (opens in a new tab).

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