查看一個簡單的jQuery的例子來遍歷一個JavaScript數組物件。
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); });
上面的程式碼片段運作正常,提示 “apple”, “orange” … 等,如預期般。
問題: JSON 字串
在下面的例子中,宣告了一個JSON字串(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,它顯示在控制台下面的錯誤:
Uncaught TypeError: Cannot use 'in' operator to search for '156'
in [{"id":"1","tagName":"apple"}...
解決方案:JSON字串轉換為JavaScript物件。
要修復它,請透過標準JSON.parse()或jQuery 的 $.parseJSON 將其轉換為JavaScript物件。
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); });