使用JSON填充JavaScript變量

我正在使用電話差距，我想用手機差距文件api讀取文件。我可以讀取文件。但是當我把我的JSON放入一個變量時，它只返回'[]'。使用JSON填充JavaScript變量

var json; 
function readFS(fileSystem) { 
      fileSystem.root.getFile("readme.txt", {create: true}, readFileEntry, fail); 
     } 

     function readFileEntry(fileEntry) { 
      fileEntry.file(gotFileread, fail); 
     } 

     function gotFileread(file){ 
      readAsText(file); 
     } 


     function readAsText(file) { 
      var reader = new FileReader(); 
      reader.onloadend = function(evt) { 
       console.log("Read as text"); 
       console.log(evt.target.result); 
       json = evt.target.result; // this returns only [] 
       navigator.notification.alert(evt.target.result); // this returns the real JSON :o 

      }; 
      reader.readAsText(file); 
     }

這是在readme.txt文件

{"games":[{"id":"2","name":"bartje","photo":"photo2.png","description":"kimpe","length":"is","totalDownloads":"0","totalFinished":"0","locations":[{"id":"3","name":"loc21","photo":"loc21.jpg","description":"loc21","FK_Game_id":"2","lat":"51.0000","long":"4.0000","status":"0"},{"id":"5","name":"loc22","photo":"loc22.jog","description":"locatie 22","FK_Game_id":"2","lat":"51.2330","long":"40.2222","status":"1"}]},{"id":"3","name":"aa","photo":"photo3.jPg","description":"aa","length":"aa","totalDownloads":"0","totalFinished":"3","locations":[{"id":"4","name":"loc4","photo":"loc4.jpg","description":"loc4","FK_Game_id":"3","lat":"51.2191","long":"4.4021","status":"0"}]}]}

我現在可以從文件中檢索數據，並把它放在一個變量的JSON。現在我唯一的問題是我不能用它作爲JSON像

json.games[0].id

我試圖做

json = eval(evt.target.result);

但是，這並不工作：○

來源

2012-01-19 Bart De Kimpe

這不會解決你的問題......但是，一旦你得到正確的JSON文本，你將需要eval（）的入JSON變量。 –

嘗試：

myJson = JSON.parse(evt.target.result);

因爲這將創建一個從你讀過的文本對象

來源

2012-01-19 15:25:45

這不起作用，它也返回[] –

我剛纔意識到它可能是與'json'的名稱衝突。嘗試調用其他變量，如'myJson'。 –

你是對的！它是'myJSON = jQuery.parseJSON（evt.target.result）'。現在我可以用它作爲真正的JSON –

這工作，所以它可能有與你如何閱讀文件有關。你在console.log(evt.target.result);中看到什麼？

var g = {"games":[{"id":"2","name":"bartje","photo":"photo2.png","description":"kimpe","length":"is","totalDownloads":"0","totalFinished":"0","locations":[{"id":"3","name":"loc21","photo":"loc21.jpg","description":"loc21","FK_Game_id":"2","lat":"51.0000","long":"4.0000","status":"0"},{"id":"5","name":"loc22","photo":"loc22.jog","description":"locatie 22","FK_Game_id":"2","lat":"51.2330","long":"40.2222","status":"1"}]},{"id":"3","name":"aa","photo":"photo3.jPg","description":"aa","length":"aa","totalDownloads":"0","totalFinished":"3","locations":[{"id":"4","name":"loc4","photo":"loc4.jpg","description":"loc4","FK_Game_id":"3","lat":"51.2191","long":"4.4021","status":"0"}]}]} 

alert(g.games[0].id) --> "2" 

alert(g.games[0].locations[0].name) --> "loc21"

來源

2012-01-19 15:22:47

我得到JSON文件前面有很多空格： –

如果evt.target.result字符串

'{"games":[{"id":"2","name":"bartje","photo":"photo2.png","description":"kimpe","length":"is","totalDownloads":"0","totalFinished":"0","locations":[{"id":"3","name":"loc21","photo":"loc21.jpg","description":"loc21","FK_Game_id":"2","lat":"51.0000","long":"4.0000","status":"0"},{"id":"5","name":"loc22","photo":"loc22.jog","description":"locatie 22","FK_Game_id":"2","lat":"51.2330","long":"40.2222","status":"1"}]},{"id":"3","name":"aa","photo":"photo3.jPg","description":"aa","length":"aa","totalDownloads":"0","totalFinished":"3","locations":[{"id":"4","name":"loc4","photo":"loc4.jpg","description":"loc4","FK_Game_id":"3","lat":"51.2191","long":"4.4021","status":"0"}]}]}';

將其轉換爲對象使用

var result = eval(evt.target.result);

，那麼你可以給

var games = dataObject.games; 
for(var i = 0; i< games.length; i++){ 
    var game = games[i]; 
    // then access properties games.id, games.name, games.photo ... etc.. 
}

來源

2012-01-19 15:52:05 Diode

var games = result.games你的意思是？但evt.target.result不會給出字符串 –

儘可能避免使用eval（）並使用更安全的JSON.parse（）。 –

使用JSON填充JavaScript變量

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