npm package: @kesplus/connect-history-api-fallback
Description: Provides a fallback for non-existing directories so that the HTML 5 history API can be used.
Author: Ben Ripkens
Latest version: 2.0.0

<h1 align="center">connect-history-api-fallback</h1>
<p align="center">Middleware to proxy requests through a specified index page, useful for Single Page Applications that utilise the HTML5 History API.</p>

<h2>Table of Contents</h2>

<!-- TOC depthFrom:2 depthTo:6 withLinks:1 updateOnSave:1 orderedList:0 -->

- [Introduction](#introduction)
- [Usage](#usage)
- [Options](#options)
	- [index](#index)
	- [rewrites](#rewrites)
	- [verbose](#verbose)
	- [htmlAcceptHeaders](#htmlacceptheaders)
	- [disableDotRule](#disabledotrule)

<!-- /TOC -->

## Introduction

Single Page Applications (SPA) typically only utilise one index file that is
accessible by web browsers: usually `index.html`. Navigation in the application
is then commonly handled using JavaScript with the help of the
[HTML5 History API](http://www.w3.org/html/wg/drafts/html/master/single-page.html#the-history-interface).
This results in issues when the user hits the refresh button or is directly
accessing a page other than the landing page, e.g. `/help` or `/help/online`
as the web server bypasses the index file to locate the file at this location.
As your application is a SPA, the web server will fail trying to retrieve the file and return a *404 - Not Found*
message to the user.

This tiny middleware addresses some of the issues. Specifically, it will change
the requested location to the index you specify (default being `/index.html`)
whenever there is a request which fulfills the following criteria:

 1. The request is a `GET` or `HEAD` request
 2. which accepts `text/html`,
 3. is not a direct file request, i.e. the requested path does not contain a
    `.` (DOT) character and
 4. does not match a pattern provided in options.rewrites (see options below)

## Usage

The middleware is available through NPM and can easily be added.

```
npm install --save connect-history-api-fallback
```

Import the library

```javascript
var history = require('connect-history-api-fallback');
```

Now you only need to add the middleware to your application like so

```javascript
var connect = require('connect');

var app = connect()
  .use(history())
  .listen(3000);
```

Of course you can also use this piece of middleware with express:

```javascript
var express = require('express');

var app = express();
app.use(history());
```

## Options
You can optionally pass options to the library when obtaining the middleware

```javascript
var middleware = history({});
```

### index
Override the index (default `/index.html`). This is the request path that will be used when the middleware identifies that the request path needs to be rewritten.

This is not the path to a file on disk. Instead it is the HTTP request path. Downstream connect/express middleware is responsible to turn this rewritten HTTP request path into actual responses, e.g. by reading a file from disk.

```javascript
history({
  index: '/default.html'
});
```

### rewrites
Override the index when the request url matches a regex pattern. You can either rewrite to a static string or use a function to transform the incoming request.

The following will rewrite a request that matches the `/\/soccer/` pattern to `/soccer.html`.
```javascript
history({
  rewrites: [
    { from: /\/soccer/, to: '/soccer.html'}
  ]
});
```

Alternatively functions can be used to have more control over the rewrite process. For instance, the following listing shows how requests to `/libs/jquery/jquery.1.12.0.min.js` and the like can be routed to `./bower_components/libs/jquery/jquery.1.12.0.min.js`. You can also make use of this if you have an API version in the URL path.
```javascript
history({
  rewrites: [
    {
      from: /^\/libs\/.*$/,
      to: function(context) {
        return '/bower_components' + context.parsedUrl.pathname;
      }
    }
  ]
});
```

The function will always be called with a context object that has the following properties:

 - **parsedUrl**: Information about the URL as provided by the [URL module's](https://nodejs.org/api/url.html#url_url_parse_urlstr_parsequerystring_slashesdenotehost) `url.parse`.
 - **match**: An Array of matched results as provided by `String.match(...)`.
 - **request**: The HTTP request object.


### verbose
This middleware does not log any information by default. If you wish to activate logging, then you can do so via the `verbose` option or by specifying a logger function.

```javascript
history({
  verbose: true
});
```

Alternatively use your own logger

```javascript
history({
  logger: console.log.bind(console)
});
```

### htmlAcceptHeaders
Override the default `Accepts:` headers that are queried when matching HTML content requests (Default: `['text/html', '*/*']`).

```javascript
history({
  htmlAcceptHeaders: ['text/html', 'application/xhtml+xml']
})
```

### disableDotRule
Disables the dot rule mentioned above:

> […] is not a direct file request, i.e. the requested path does not contain a `.` (DOT) character […]

```javascript
history({
  disableDotRule: true
})
```