IndexDBFileSystem.js emulates a case insensitive file system using IndexDB. All files are stored as blob objects, which should make them actually be stored as files by the browser engine. This file system is intended to be used with Web Assembly to emulate a file layer. There isn't a maximum disk space to querry for, and some browser engines automatically clear their IndexDB Databases automatically (every 14 days). It's best to think of this library as semi-permanent storage, like a cache. WPA apps can request that their databses be permanent.
IndexDBFileSystem has a mostly async API. First, you need to create an IndexDBFileSystem object. Most functions on this object don't return anything directly, instead they rely on callbacks. Function names that start with a capital letter are a part of IndexDBFileSystem's public API. Functions that start with a lower case letter are considered private API. All variables are assumed to be private. IndexDBFileSystem has C++ bindings that allow it to be used with web-assembly. The C++ API closeley resembles the javascript API.
constructor(databaseName: string, onSuccess: function, onError: function)
The constructor takes a database name, a success callback and an error callback. The success callback takes one argument the IndexDBFileSystem object that was just constructed. If you want to use the constructed object without waiting for the callback, it has a IsReady member, which is a boolean. The file system can be used inside a web assembly module, it includes seperate injection and initialization code for web assembly.
onSuccess(self: IndexDBFileSystem): void
onError(errorMessage: string): void
The error callback takes a single argument, the error string and has no return. The success callback is a reference to the IndexDBFileSystem object that was just created.
Write(fileName: string, fileContent: blob, OnSuccess: function, OnError: function): void
Writes some bytes of data to disk. The write function takes a file name, a blob for the file content, and callbacks for success and failure. If the file being written does not exist, it will be created. If the file being written already exists, it's content will be replaced. There is no append function, but it can be implemented with read and write. If the file path is in a directory which does not exist, that directory will be created.
OnSuccess(fileName: string, bytesWritten: int): void
OnError(errorMessage: string): void
The error callback takes a single argument, the error string and has no return. The success callback takes the path of the file that was written, and the number of bytes that where written.
Read(fileName: string, OnSuccess: function, OnError: function): void
Reads some bytes of data from the disk. If the the file does not exist, the error callback is called. If the file does exist, but is empty, the success callback will have null for it's blob data.
OnSuccess(filePath: string, fileContent: blob): void
OnError(errorMessage: string) : void
The success callback takes the path of the file that was read and a blob of file data. If the file is empty, the blob will be null. The error callback takes a single argument, the error string and has no return.
CreateFile(path: string, OnSuccess: function, OnError: function): void
Created a new file, under the hood this function writes 0 bytes to a file using the Write function.
OnSuccess(fileName: string): void
OnError(errorMessage: string): void
The error callback takes a single argument, the error string and has no return. The only argument of the success callback is the path of the file that was created.
CreateFolder(path: string, OnSuccess: function, OnError: function): void
Creates a new folder. The file system isn't touched, folders exist only as meta-data.
OnSuccess(path: string): void
OnError(error: string): void
The error callback takes a single argument, the error string and has no return. The only argument of the success callback is the path of the folder that was created.
Delete(path: string, OnSuccess: function, OnError: function): void
The Delete function is used to remove both files and folders.
OnSuccess(path: string): void
OnError(error: string): void
The error callback takes a single argument, the error string and has no return. The only argument of the success callback is the path of the file or folder that was removed.
IsDirectory(path: string, callback: function): void
Checks if the provided path is a directory. Under the hood, this function calls Exists
callback(path: string, isDirectory: bool): void
The directory check callback returns the path of the folder being checked, and a boolen indicating weather of not it's a folder.
IsFile(path: string, callback: function): void
Checks if the provided path is a file. Under the hood, this function calls Exists
callback(path: string, isFile: bool): void
The file check callback returns the path of the file being checked, and a boolen indicating weather of not it's a file.
Exists(path: string, callback: function): void
The Exists function checks if a given path exists. We can use this function to check if a path is a file, folder, or if it doesn't exist.
callback(path: string, isDirectory: bool, isFile: bool): void
The callback to Exists takes the path of the file being checked, and two booleans to tell if the path is a directory or folder. If both booleans are false, the path does not exist.
DepthFirstTraversal(path: string, preOrder: bool, callback: function, finished: function): void
Used to traverse a given directory, the second argument specifies if the traversal is pre or post order. There are also PreOrderDepthFirstTraversal and PostOrderDepthFirstTraversal functions that don't take this additional paramater.
callback(path: string, depth: int, isDirectory: bool, isFile: bool): void
finished(path: string): void
The callback function is called for every directory being traversed. It includes the full path of the directory or file, it's depth and booleans to tell if it's a file or folder. When iteration is finished, the finished callback is called with the original path.