Javascript：TypeError：循环对象值
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Javascript: TypeError: cyclic object value
提问by Neil P
I am trying to stringify a javascript object, however when I do this a get the following error:
我正在尝试对一个 javascript 对象进行字符串化，但是当我这样做时，会出现以下错误：
TypeError: cyclic object value
类型错误：循环对象值
I don't believe that my code contains any cyclic references (newServiceObject is not referenced inside the object), so I do not understand why I am getting this message.
我不相信我的代码包含任何循环引用（对象内部没有引用 newServiceObject），所以我不明白为什么我会收到这条消息。
I want to turn my object that contains two properties and an array into a single string.
我想将包含两个属性和一个数组的对象转换为单个字符串。
var serviceName = $('#newServiceNameBox').val();
var serviceCodeElemList = $(".ServiceCodeName").map(function() { return $(this).html(); } );
//create the new service object
var newServiceObject = {ServiceId:-1, ServiceName: serviceName, ServiceCodes: serviceCodeElemList };
var appendNewService = '&newService='+JSON.stringify(newServiceObject);
The error occurs on the last line (the JSON.Stringify() ) but I have no idea why!
错误发生在最后一行（ JSON.Stringify() ），但我不知道为什么！
采纳答案by Juan Mendes
This is typically because you are trying to serialize a JavaScript object that has properties that point to each other in a cycle.
这通常是因为您试图序列化一个 JavaScript 对象，该对象的属性在一个循环中相互指向。
In your example, newServiceObject.serviceCodeElemListpoints to a jQueryobject which does have cycles in it: Its contextproperty which points to a document object. A document object has pointers to DOM elements that have pointers back to the document through the ownerDocumentproperty
在您的示例中，newServiceObject.serviceCodeElemList指向一个jQuery包含循环的对象：它的context属性指向一个文档对象。文档对象具有指向 DOM 元素的指针，这些元素通过ownerDocument属性 返回指向文档的指针
var jqueryObj = $('div');
console.log(jqueryObj.context); // Document object
console.log(jqueryObj.context.body.firstChild.ownerDocument); // Document object
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div></div>回答by Neil P
Found it!
找到了！
My problem was that when using jquery to build the array, I should have included the ToArray() method after the map function.
我的问题是，当使用 jquery 构建数组时，我应该在 map 函数之后包含 ToArray() 方法。
var serviceCodeElemList = $(".ServiceCodeName").map(function() { return $(this).html(); } ).ToArray();
Therefore when the array is included in the object, it is a standard array and not a jquery object.
因此，当数组包含在对象中时，它是一个标准数组，而不是一个 jquery 对象。
