sample usage of the phonegap file api

fileapisample

var writeData = function (filename, data, callback) {
	var writeOutData = function () {
		var fw = new FileWriter();
		fw.oncomplete = callback;
		fw.onerror = function () { 
			alert("Failed to save update");
		}
		fw.writeAsText("myDir/" + filename, data);
	}
	
	navigator.fileMgr.testDirectoryExists("myDir", function(exists) {
			exists ? writeOutData() :
			navigator.fileMgr.createDirectory("myDir", writeOutData, function() {
				alert("Failed to save update");
			})
	});
};

var readData = function (filename, callback) {
	var filePath = "myDir/" + filename;
	
	var readInData = function () {
		var fr = new FileReader();
		fr.onload = function (data) {
			callback(data);
		};
		fr.readAsText(filePath);
	}		
	
	navigator.fileMgr.testFileExists(filePath, function(exists) {
		exists ? readInData() : alert("file doesn't exist");
	});
}