Chrome应用程序:无法检索文件加载状态

我的Chrome应用程序有一个函数，它要求另一个函数加载一个文件，检查该函数是否设置了表示成功的标志（External.curFile.lodd），然后尝试处理它。我的问题是，第一次调用该函数时没有设置标志，但第二次调用时已经设置了标志。

我有一种感觉，这与Chrome文件函数是异步的有关，所以我在加载文件时让第一个函数空闲了一段时间。不管我等多久，第一次加载都不会成功，但第二次加载总是成功！

调用功能：

function load_by_lines_from_cur_dir( fileName, context ){ // determine the 'meaning' of a file line by line, return last 'meaning', otherwise 'null' 
    var curLineMeaning = null;
    var lastLineValid = true;
    External.read_file_in_load_path(fileName); // 'External' load 'fileName' and reads lines, REPLacement does not see this file
    // This is a dirty workaround that accounts for the fact that 'DirectoryEntry.getFile' is asynchronous, thus pre-parsing checks fail intil loaded
    var counter = 0, maxLoops = 10;
    nuClock();
    do{ 
        sleep(500); 
        counter++; 
        preDebug.innerText += ''r'nLoop:' + counter + " , " + time_since_last();
    }while( !External.curFile.lodd && (counter < maxLoops) ); //idle and check if file loaded, 5000ms max
    preDebug.innerText += ''r'nLoaded?:' + External.curFile.lodd;
    preDebug.innerText += ''r'nLines?:' +  External.curFile.lins;
    if( External.curFile.lodd ){ // The last load operating was successful, attempt to parse and interpret each line
        // parse and interpret lines, storing each meaning in 'curLineMeaning', until last line is reached
        while(!External.curFile.rEOF){ 
            curLineMeaning = meaning( s( External.readln_from_current_file() ), context); 
            preDebug.innerText += ''r'nNext Line?: ' + External.curFile.lnnm;
            preDebug.innerText += ''r'nEOF?: ' + External.curFile.rEOF;
        }
    } // else, return 'null'
    return curLineMeaning; // return the result of the last form
}

它调用以下内容：

External.read_file_in_load_path = function(nameStr){ // Read the lines of 'nameStr' into 'External.curFile.lins'
    External.curPath.objt.getFile( // call 'DirectoryEntry.getFile' to fetch a file in that directory 
        nameStr,
        {create: false},
        function(fileEntry){ // action to perform on the fetched file, success
            External.curFile.name = nameStr; // store the file name for later use
            External.curFile.objt = fileEntry; // store the 'FileEntry' for later use
            External.curFile.objt.file( function(file){ // Returns 'File' object associated with selected file. Use this to read the file's content.
                var reader = new FileReader();
                reader.onload = function(e){
                    External.curFile.lodd = true; // File load success
                };
                reader.onloadend = function(e){
                    //var contents = e.target.result;
                    // URL, split string into lines: http://stackoverflow.com/questions/12371970/read-text-file-using-filereader
                    External.curFile.lins = e.target.result.split(''n'); // split the string result into individual lines
                };
                reader.readAsText(file);
                External.curFile.lnnm = 0; // Set current line to 0 for the newly-loaded file
                External.curFile.rEOF = false; // Reset EOF flag
                // let's try a message instead of a flag ...
                /*chrome.runtime.sendMessage({greeting: "hello"}, function(response) {
                    console.log(response.farewell);
                });*/
            } );
        },
        function(e){ External.curFile.lodd = false; } // There was an error
    );
};

此应用程序是Scheme的方言。重要的是应用程序要知道源文件是否已加载。