https://github.com/sharkcore/tweenz

Tweens for Express
https://github.com/sharkcore/tweenz

express middleware node nodejs pyramid tween

Last synced: 8 days ago
JSON representation

Tweens for Express

• Host: GitHub
• URL: https://github.com/sharkcore/tweenz
• Owner: sharkcore
• Created: 2017-11-30T02:13:49.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2020-06-02T23:46:55.000Z (over 4 years ago)
• Last Synced: 2024-04-26T03:21:21.006Z (5 months ago)
• Topics: express, middleware, node, nodejs, pyramid, tween
• Language: JavaScript
• Size: 118 KB
• Stars: 7
• Watchers: 4
• Forks: 1
• Open Issues: 10
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

• awesome-express - tweenz - A library for writing Express middleware, inspired by Pyramid tweens. (Middleware)

README

        
# tweenz

[![npm (scoped)](https://img.shields.io/npm/v/tweenz.svg)](https://yarn.pm/tweenz)

[![Build Status](https://travis-ci.org/sharkcore/tweenz.svg?branch=master)](https://travis-ci.org/sharkcore/tweenz)

[![Greenkeeper badge](https://badges.greenkeeper.io/sharkcore/tweenz.svg)](https://greenkeeper.io/)

A small library for writing [Express](https://expressjs.com/) middleware, inspired by

[Pyramid tweens](https://docs.pylonsproject.org/projects/pyramid/en/latest/narr/hooks.html#registering-tweens).

### Why?

This library does the following:

-   Exposes the response body to the middleware (as part of `requestDetails`)

-   Provides a first class API to allow middleware to safely execute code after the request has finished

_**Please Note!** This middleware stores the whole response body in memory. If you are returning particularly large responses, you should be aware of this._

## Getting started

```bash

yarn add tweenz

```

A tween in `tweenz` looks like this:

```js

export default () => {

    // one-time configuration code goes here

    return async (requestDetails, req, res) => {

        // code to be executed for each request before

        // the actual application code goes here

        const details = await requestDetails;

        // code to be executed for each request after

        // the actual application code goes here

    };

};

```

### Example

Here's a tween to calculate the time taken for a request to complete:

#### time-logger.js

```js

export default () => {

    return async (requestDetails, req, res) => {

        const startAt = process.hrtime();

        // wait for request to complete

        await requestDetails;

        // calculate time taken for request

        const [seconds, nanoseconds] = process.hrtime(startAt);

        const miliseconds = seconds * 1e3 + nanoseconds * 1e-6;

        console.log(`Request took ${miliseconds}ms to complete!`);

    };

};

```

#### app.js

```js

import express from 'express';

import tweenz from 'tweenz';

import timeLogger from './time-logger';

const app = express();

app.use(tweenz(timeLogger()));

...

```

## API

### Registering tweens

```

tweenz(tween [, tween ...])

```

### Tween Callback

A tween is a callback, which will get executed with the following arguments

-   **`requestDetails`**

    An object of the following type:

    ```js

    {

        responseBody: string;

    }

    ```

-   **`req`**

    [Express request object](http://expressjs.com/en/api.html#req)

-   **`res`**

    [Express response object](http://expressjs.com/en/api.html#res)