connect-history-api-fallback
Middleware to proxy requests through a specified index page, useful for Single Page Applications that utilise the HTML5 History API.
Table of Contents
- [Introduction](#introduction)
- [Usage](#usage)
- [Options](#options)
- [index](#index)
- [rewrites](#rewrites)
- [verbose](#verbose)
- [htmlAcceptHeaders](#htmlacceptheaders)
- [disableDotRule](#disabledotrule)
## 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
})
```