IDBFS is partly based on the `fs` module from node.js. The API is asynchronous and most methods require the caller to provide a callback function. Errors are passed to callbacks through the first parameter.
To create a new file system or open an existing one, create a new `FileSystem` instance and pass the name of the file system. A new IndexedDB database is created for each file system.
#### Example
````
<script>
var fs = new IDBFS.FileSystem('local');
fs.open('/myfile', 'w+', function(err, fd) {
if (err) throw err;
fs.close(fd, function(err) {
if (err) throw err;
fs.stat('/myfile', function(err, stats) {
if (err) throw err;
console.log('stats: ' + JSON.stringify(stats));
});
});
});
</script>
````
As with node.js, there is no guarantee that file system operations will be executed in the order they are invoked. Ensure proper ordering by chaining operations in callbacks.
### API Reference
Callbacks for methods that accept them are non-optional. The first callback parameter is reserved for passing errors. It will be `undefined` if no errors occurred and should always be checked.
#### IDBFS.FileSystem(name, flags)
File system constructor, invoked to open an existing file system or create a new one. Accepts a name and optional flags. Use `'FORMAT'` to force IDBFS for format the file system.
#### fs.stat(path, callback)
Asynchronous stat(2). Callback gets `(error, stats)`, where `stats` is an object like
{
node: <string> // internal node id (unique)
dev: <string> // file system name
size: <number> // file size in bytes
nlinks: <number> // number of links
atime: <number> // last access time
mtime: <number> // last modified time
ctime: <number> // creation time
type: <string> // file type (FILE, DIRECTORY, ...)
}
#### fs.fstat(fd, callback)
Asynchronous stat(2). Callback gets `(error, stats)`. See `fs.stat`.
#### fs.link(oldpath, newpath, callback)
Asynchronous link(2). Callback gets no additional agruments.
#### fs.unlink(path, callback)
Asynchronous unlink(2). Callback gets no additional agruments.
#### fs.rmdir(path, callback)
Asynchronous rmdir(2). Callback gets no additional agruments.
#### fs.mkdir(path, callback)
Asynchronous mkdir(2). Callback gets no additional agruments.
#### fs.close(fd, callback)
Asynchronous close(2). Callback gets no additional agruments.
#### fs.open(path, flags, callback)
Asynchronous open(2). Flags can be
*`'r'`: Open file for reading. An exception occurs if the file does not exist.
*`'r+'`: Open file for reading and writing. An exception occurs if the file does not exist.
*`'w'`: Open file for writing. The file is created (if it does not exist) or truncated (if it exists).
*`'w+'`: Open file for reading and writing. The file is created (if it does not exist) or truncated (if it exists).
*`'a'`: Open file for appending. The file is created if it does not exist.
*`'a+'`: Open file for reading and appending. The file is created if it does not exist.
Callback gets `(error, fd)`, where `fd` is the file descriptor.
Unlike node.js, IDBFS does not accept the optional `mode` parameter since it doesn't yet implement file permissions.
Write bytes from `buffer` to the file specified by `fd`, where `offset` and `length` describe the part of the buffer to be written. The `position` refers to the offset from the beginning of the file where this data should be written. If `position` is `null`, the data will be written at the current position. See pwrite(2).
The callback gets `(error, nbytes)`, where `nbytes` is the number of bytes written.
Read bytes from the file specified by `fd` into `buffer`, where `offset` and `length` describe the part of the buffer to be used. The `position` refers to the offset from the beginning of the file where this data should be read. If `position` is `null`, the data will be written at the current position. See pread(2).
The callback gets `(error, nbytes)`, where `nbytes` is the number of bytes read.
#### fs.lseek(fd, offset, whence, callback)
Asynchronous lseek(2), where `whence` can be `SET`, `CUR`, or `END`. Callback gets `(error, pos)`, where `pos` is the resulting offset, in bytes, from the beginning of the file.
Asynchronous readdir(3). Reads the contents of a directory. Callback gets `(error, files)`, where `files` is an array containing the names of each file in the directory, excluding `.` and `..`.
