Development

To aid in the development of new libraries of triggers and functions, you can use the type declaration files for the [triggers and functions API]({{< relref "/operate/oss_and_stack/stack-with-enterprise/deprecated-features/triggers-and-functions/concepts/JavaScript_API" >}}), which allows your preferred development environment to provide autocompletion and type checking. You can install this information using the following command:

bash

npm install https://gitpkg.now.sh/RedisGears/RedisGears/js_api --save-dev

Or you can manually add it as a devDependency to your package.json file:

json

"devDependencies": {
  "@redis/gears-api": "https://gitpkg.now.sh/RedisGears/RedisGears/js_api"
}

Example project setup

Create an empty directory for your new triggers and functions project, my_first_project. Navigate to the folder and run the following command:

bash

$ npm init -y -f
npm WARN using --force Recommended protections disabled.
Wrote to /home/work/my_first_project/package.json:

{
  "name": "my_first_project",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

Update the package.json to add the gears API to the devDependencies object.

{
  "name": "my_first_project",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "devDependencies": {
    "@redis/gears-api": "https://gitpkg.now.sh/RedisGears/RedisGears/js_api"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

Install the dependencies using npm install.

Create a new file, index.js and import the gears-api module. While this step is not strictly necessary, doing so will enable code intelligent code completion when adding the registerFunction:

JavaScript

#!js name=lib api_version=1.0

import { redis } from '@redis/gears-api';

redis.registerFunction("test", ()=>{
    return "test";
});

To automate the deployment, update the scripts section in package.json:

json

"scripts": {
  "deploy": "gears-api index.js"
}

Now you can deploy your code to Redis Stack using the following command:

bash

> npm run deploy -- -r redis://localhost:6379

> deploy
> gears-api index.js

Deployed! :)

The provided URL should follow the following format:

<redis[s]://[[username][:password]@][host][:port][/db-number]>

You can now run your Redis Stack function:

bash

127.0.0.1:6379> TFCALL lib.test 0
"test"

Example function using a third-party `npm` package

If you want to use a third-party npm package in your Redis Stack function, the overall process is nearly the same as already discussed, with just a couple of differences.

First, you'll need to install your package using npm install. For this example, the pi symbol from the math.js library will be used in a simple function that calculates the area of a circle.

bash

npm install mathjs

Note: your package.json file will also be updated with the new dependency. For example:

json

"dependencies": {
    "mathjs": "^12.0.0"
}

Next, you'll import the required symbol(s) into your function.

javascript

#!js api_version=1.0 name=lib

import { redis } from '@redis/gears-api';
import { pi } from 'mathjs';

function calculateCircleArea(client, radius) {
  return pi * radius * radius;
}

redis.registerFunction('calculateArea', calculateCircleArea);

Load and run your new function as described in the previous section.

Example project setup

Example function using a third-party npm package

Example function using a third-party `npm` package