var json = [
{"id":"1","tagName":"apple"},
{"id":"2","tagName":"orange"},
{"id":"3","tagName":"banana"},
{"id":"4","tagName":"watermelon"},
{"id":"5","tagName":"pineapple"}
];
$.each(json, function(idx, obj) {
alert(obj.tagName);
});
上麵的代碼片斷工作正常，提示 “apple”, “orange” … 等，如預期一樣。問題: JSON 字符串
下麵的例子中，聲明了一個JSON字符串（隨附單或雙引號）直接地。
var json = '[{"id":"1","tagName":"apple"},{"id":"2","tagName":"orange"},
{"id":"3","tagName":"banana"},{"id":"4","tagName":"watermelon"},
{"id":"5","tagName":"pineapple"}]';
$.each(json, function(idx, obj) {
alert(obj.tagName);
});
在Chrome中，它顯示在控製台下麵的錯誤：
Uncaught TypeError: Cannot use 'in' operator to search for '156'
in [{"id":"1","tagName":"apple"}...
解決方案：JSON字符串轉換為JavaScript對象。要修複它，通過標準JSON.parse()或jQuery 的 $.parseJSON 將其轉換為JavaScript對象。
var json = '[{"id":"1","tagName":"apple"},{"id":"2","tagName":"orange"},
{"id":"3","tagName":"banana"},{"id":"4","tagName":"watermelon"},
{"id":"5","tagName":"pineapple"}]';
$.each(JSON.parse(json), function(idx, obj) {
alert(obj.tagName);
});
//or
$.each($.parseJSON(json), function(idx, obj) {
alert(obj.tagName);
});
參考：
