JSON.parse不工作在PhoneGap [英] JSON.parse not working in PhoneGap

问题描述

我正在开发一个程序，需要将用户数据保存在文件中作为JSON格式。它正在以JSON格式保存我的数据，但是当我尝试使用 JSON.parse 来解析我存储的JSON时，它不工作。
这是我存储数据的代码：

I'm working on a program that needs to save user data in a file as a JSON format. It is doing fine saving my data as JSON but when I try to use JSON.parse to parse my stored JSON it doesn't work. Here is my code for storing the data:

function writeUser(data) {
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fs){
        fs.root.getFile('user.data', {create: true, exclusive: false}, function(fe){
            fe.createWriter(function(writer){
                //Its converts my data to JSON here
                writer.write(JSON.stringify(data));
                //It displays this so I knows its been written!
                console.log('File written');
            }, failwrite);
        }, failwrite);
    }, failwrite);
}
function failwrite(error) {
    console.log(error.code);
}

这里是读取我的数据的代码：

And here is the code that read my data:

function readUser(){
    window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function(fs){
        fs.root.getFile('user.data', null, function(fe){
            fe.file(function(file){
                return readAsText(file);
            }, failread);
        }, failread);
    }, failread);
}
function readAsText(file) {
    var reader = new FileReader();
    reader.onloadend = function(evt) {
        console.log(evt.target.result);
    };
    return reader.readAsText(file);
}

它返回我的数据作为字符串，这是我得到作为一个string {status：true，id：1，password：xx} ，但是当我使用JSON.parse它返回未识别的对象。这里是它使用的部分 JSON.parse ：

Its returns my data fine as a string, Here is what I get as a string {"status":"true","id":"1","password":"xx"}, But when I use JSON.parse with my data it returns unidentified object. Here is the part where it uses JSON.parse:

readUser();
var user = JSON.parse(readUser());
console.log(user);

它甚至不会运行我的console.log命令与解析的JSON。

It won't even run my console.log command with the parsed JSON.

推荐答案

readUser不返回任何内容。该文件的内容在readAsText回调中可用。你必须json解析evt.target.result并从那里继续。

the readUser does not return anything. the content of the file is available in the readAsText callback. you have to json parse the evt.target.result and continue from there.

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