How to check a file's existence in phone directory with phonegap

Question

I\'m writing an Android application with Phonegap 1.4.1 and Sencha that downloads and reads pdf files. How can I check whether the file exists in the phone directory using e

Answer 1

If you need a boolean-compatible method...

function checkIfFileExists(path){
    var result = false;

    window.requestFileSystem(
        LocalFileSystem.PERSISTENT, 
        0, 
        function(fileSystem){
            fileSystem.root.getFile(
                path, 
                { create: false }, 
                function(){ result = true; }, // file exists
                function(){ result = false; } // file does not exist
            );
        },
        getFSFail
    ); //of requestFileSystem

    return result;
}

Answer 2

@PassKit is correct, in my case i needed to add an eventlistener

document.addEventListener("deviceready", onDeviceReady, false);
function onDeviceReady() {
       window.requestFileSystem = window.requestFileSystem || window.webkitRequestFileSystem;
       window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, fsSuccess, fsError);
}

then for the value "fileSystemRoot" in the funtion "fsSuccess"

var fileSystemRoot; // Global variable to hold filesystem root

function fsSuccess(fileSystem) {
       fileSystemRoot = fileSystem.root.toURL();
}

the function "checkFileExists"

function checkFileExists(fileName) {
    var http = new XMLHttpRequest();
    http.open('HEAD', fileName, false);
    http.send(null);
    if (http.status.toString() == "200") {
        return true;
    }
    return false
}

for check if the file exists

if (checkFileExists(fileSystemRoot + "fileName")) {
     // File Exists
} else {
     // File Does Not Exist
}

the var fileSystemRoot in IOS return me "cdvfile://localhost/persistent/" and the files was store in "//var/mobile/Containers/Data/Application/{AppID}/Documents"

Many thanks to @PassKit, this run in synchronous mode and was tested in IOS 8.1