LocalFileSystem - Web APIs
window.requestfilesystem(window.persistent, 1024*1024,oninitfs,errorhandler); method overview void requestfilesystem (in unsigned short type, in unsigned long long size, in filesystemcallback successcallback, in optional errorcallback errorcallback); void resolvelocalfilesystemurl (in domstring url, in entrycallback successcallback, in optional errorcallback errorcallback); constants constant value description temporary 0 transient storage that can be be removed by the browser at its discretion.
... resolvelocalfilesystemurl() lets you look up the entry for a file or directory with a local url.
... void resolvelocalfilesystemurl( in domstring url, in entrycallback successcallback, in optional errorcallback errorcallback ); parameters url the url of a local file in the file system.

DirectoryReaderSync - Web APIs
you can also use the filesystem: url to look up the entry with resolvelocalfilesystemurl().
... window.resolvelocalfilesystemurl = window.resolvelocalfilesystemurl || window.webkitresolvelocalfilesystemurl; // create web workers 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) { // print out file's name.

File and Directory Entries API support in Firefox - Web APIs
the localfilesystem.resolvelocalfilesystemurl() method isn't implemented.

Introduction to the File and Directory Entries API - Web APIs
the asynchronous api has the following global methods: requestfilesystem() and resolvelocalfilesystemurl().

File and Directory Entries API - Web APIs
they're available on the window object and implemented in localfilesystem: requestfilesystem() and resolvelocalfilesystemurl().

LocalFileSystemSync - Web APIs
void resolvelocalfilesystemurl( in domstring url ); parameter url the url of a local file in the file system.