Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
The DirectoryReaderSync
interface of the File System API lets you read the entries in a directory.
Note: This interface has been abandoned: it was on a standard track and it proves not a good idea. Do not use it anymore.
This document was last updated on March 2, 2012 and follows the W3C Specifications (Working Draft) drafted on April 19, 2011.
This specification is pretty much abandoned, having failed to reach any substantial traction.
Before you call the only method in this interface, readEntries()
, create the DirectoryEntrySync
object. But DirectoryEntrySync (as well as FileEntrySync) is not a data type that you can pass between a calling app and Web Worker thread. It's not a big deal, because you don't really need to have the main app and the worker thread see the same JavaScript object; you just need them to access the same files. You can do that by passing a list of filesystem:
URLs—which are just strings—instead of a list of entries. You can also use the filesystem:
URL to look up the entry with resolveLocalFileSystemURL()
. That gets you back to a DirectoryEntrySync (as well as FileEntrySync) object.
Example
In the following code snippet from HTML5Rocks, we create Web Workers and pass data from it to the main app.
window.resolveLocalFileSystemURL = window.resolveLocalFileSystemURL ||
window.webkitResolveLocalFileSystemURL;
var worker = new Worker('worker.js');
worker.onmessage = function(e) {
var urls = e.data.entries;
urls.forEach(function(url, i) {
window.resolveLocalFileSystemURL(url, function(fileEntry) {
console.log(fileEntry.name);
});
});
};
worker.postMessage({'cmd': 'list'});
The following is Worker.js code that gets the contents of the directory.
self.requestFileSystemSync = self.webkitRequestFileSystemSync ||
self.requestFileSystemSync;
var paths = [];
function getAllEntries(dirReader) {
var entries = dirReader.readEntries();
for (var i = 0, entry; entry = entries[i]; ++i) {
paths.push(entry.toURL());
if (entry.isDirectory) {
getAllEntries(entry.createReader());
}
}
}
function onError(e) {
postMessage('ERROR: ' + e.toString());
}
self.onmessage = function(e) {
var data = e.data;
if (!data.cmd || data.cmd != 'list') {
return;
}
try {
var fs = requestFileSystemSync(TEMPORARY, 1024*1024 );
getAllEntries(fs.root.createReader());
self.postMessage({entries: paths});
} catch (e) {
onError(e);
}
};
Returns a lost of entries from a specific directory. Call this method until an empty array is returned.
EntrySync readEntries (
) raises (FileException);
Returns
Parameter
None
Exceptions
This method can raise a FileException with the following codes: