isBinaryFile
============

Detects if a file is binary in Node.js. Similar to [Perl's `-B`




switch](http://stackoverflow.com/questions/899206/how-does-perl-know-a-file-is-binary),
in that:

* it reads the first few thousand bytes of a file
* checks for a `null` byte; if it's found, it's binary
* flags non-ASCII characters. After a certain number of "weird" characters, the
file is flagged as binary

All the logic is also pretty much ported from
[ag](https://github.com/ggreer/the_silver_searcher).

Note: if the file doesn't exist or it is empty, this function returns `false`.

## Installation

```
npm install isBinaryFile
```

## Usage

If you pass in one argument, this module assumes it's just the file path, and
performs the appropriate file read and stat functionality internally, as sync
options:

``` javascript
var isBinaryFileSync = require("isbinaryfile");

if (isBinaryFileSync(process.argv[2]))
  console.log("It is!")
else
  console.log("No.")
```

Ta da.

However, if you've already read and `stat()`-ed a file (for some other reason),
you can pass in both the file's raw data and the stat's `size` info to save
time:

```javascript
fs.readFile(process.argv[2], function(err, data) {
  fs.lstat(process.argv[2], function(err, stat) {
    if (isBinaryFileSync(data, stat.size))
      console.log("It is!")
    else
      console.log("No.")
  });
});
```

### Async

Previous to version 2.0.0, this program always ran in sync mode. Now, there's
an async option. Simply pass a function as your second parameter, and isBinaryFile
will figure the rest out:

``` javascript
var isBinaryFileSync = require("isbinaryfile");

isBinaryFileSync(process.argv[2], function(err, result) {
  if (err) return console.error(err);

  if (result)
    console.log("It is!")
  else
    console.log("No.")
}
```

## Testing

Install mocha on your machine:

```
npm install mocha -g
```

Then go into the _tests_ directory, and type `mocha test.js`.

# MIT License

Copyright (c) 2013 Garen J. Torikian

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
