jquery each報 Uncaught TypeError: Cannot use 'in' operator to search for錯誤
阿新 • • 發佈:2019-02-03
在寫前端的時候用jquery來遍歷後臺傳來的json陣列時候遇到這個錯誤:Uncaught TypeError: Cannot use 'in' operator to search for。後來查到原因是因為:一部分瀏覽器後端傳過來的是json物件,但是我們前端是需要Javascript的物件,所以需要做個轉換JSON.parse() or jQuery $.parseJSON
Review a simple jQuery example to loop over a JavaScript array object.
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);
});
Above code snippet is working fine, prompts the “apple”, “orange” … as expected.
Problem : JSON string
Review below example, declares a JSON string (enclosed with single or double quotes) directly.
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);
});
In Chrome, it shows following errors in console :
Uncaught TypeError: Cannot use 'in' operator to search for '156'
in [{"id":"1","tagName":"apple"}...
Solution : Convert JSON string to JavaScript object
To fix it, converts it to Javascript object via standard JSON.parse()
or jQuery $.parseJSON
.
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);
});
NoteMost web applications will return JSON formatted string directly, you need to convert it to JavaScript object before parse it with jQuery. 參考連結:http://www.mkyong.com/jquery/jquery-loop-over-json-string-each-example/