我有一个大对象要转换成JSON并发送。然而，它具有圆形结构。我想丢弃任何存在的循环引用，并发送任何可以字符串化的引用。我该怎么做？
谢谢
var obj = {
a: "foo",
b: obj
}
我想将对象字符串化为：
{"a":"foo"}
当前回答
var a={b:"b"};
a.a=a;
JSON.stringify(preventCircularJson(a));
评估结果为：
"{"b":"b","a":"CIRCULAR_REFERENCE_REMOVED"}"
具有以下功能：
/**
* Traverses a javascript object, and deletes all circular values
* @param source object to remove circular references from
* @param censoredMessage optional: what to put instead of censored values
* @param censorTheseItems should be kept null, used in recursion
* @returns {undefined}
*/
function preventCircularJson(source, censoredMessage, censorTheseItems) {
//init recursive value if this is the first call
censorTheseItems = censorTheseItems || [source];
//default if none is specified
censoredMessage = censoredMessage || "CIRCULAR_REFERENCE_REMOVED";
//values that have allready apeared will be placed here:
var recursiveItems = {};
//initaite a censored clone to return back
var ret = {};
//traverse the object:
for (var key in source) {
var value = source[key]
if (typeof value == "object") {
//re-examine all complex children again later:
recursiveItems[key] = value;
} else {
//simple values copied as is
ret[key] = value;
}
}
//create list of values to censor:
var censorChildItems = [];
for (var key in recursiveItems) {
var value = source[key];
//all complex child objects should not apear again in children:
censorChildItems.push(value);
}
//censor all circular values
for (var key in recursiveItems) {
var value = source[key];
var censored = false;
censorTheseItems.forEach(function (item) {
if (item === value) {
censored = true;
}
});
if (censored) {
//change circular values to this
value = censoredMessage;
} else {
//recursion:
value = preventCircularJson(value, censoredMessage, censorChildItems.concat(censorTheseItems));
}
ret[key] = value
}
return ret;
}
其他回答
var a={b:"b"};
a.a=a;
JSON.stringify(preventCircularJson(a));
评估结果为：
"{"b":"b","a":"CIRCULAR_REFERENCE_REMOVED"}"
具有以下功能：
/**
* Traverses a javascript object, and deletes all circular values
* @param source object to remove circular references from
* @param censoredMessage optional: what to put instead of censored values
* @param censorTheseItems should be kept null, used in recursion
* @returns {undefined}
*/
function preventCircularJson(source, censoredMessage, censorTheseItems) {
//init recursive value if this is the first call
censorTheseItems = censorTheseItems || [source];
//default if none is specified
censoredMessage = censoredMessage || "CIRCULAR_REFERENCE_REMOVED";
//values that have allready apeared will be placed here:
var recursiveItems = {};
//initaite a censored clone to return back
var ret = {};
//traverse the object:
for (var key in source) {
var value = source[key]
if (typeof value == "object") {
//re-examine all complex children again later:
recursiveItems[key] = value;
} else {
//simple values copied as is
ret[key] = value;
}
}
//create list of values to censor:
var censorChildItems = [];
for (var key in recursiveItems) {
var value = source[key];
//all complex child objects should not apear again in children:
censorChildItems.push(value);
}
//censor all circular values
for (var key in recursiveItems) {
var value = source[key];
var censored = false;
censorTheseItems.forEach(function (item) {
if (item === value) {
censored = true;
}
});
if (censored) {
//change circular values to this
value = censoredMessage;
} else {
//recursion:
value = preventCircularJson(value, censoredMessage, censorChildItems.concat(censorTheseItems));
}
ret[key] = value
}
return ret;
}
使用带有自定义替换符的JSON.stringify。例如：
// Demo: Circular reference
var circ = {};
circ.circ = circ;
// Note: cache should not be re-used by repeated calls to JSON.stringify.
var cache = [];
JSON.stringify(circ, (key, value) => {
if (typeof value === 'object' && value !== null) {
// Duplicate reference found, discard key
if (cache.includes(value)) return;
// Store value in our collection
cache.push(value);
}
return value;
});
cache = null; // Enable garbage collection
本例中的替换符并非100%正确（取决于您对“重复”的定义）。在以下情况下，将丢弃一个值：
var a = {b:1}
var o = {};
o.one = a;
o.two = a;
// one and two point to the same object, but two is discarded:
JSON.stringify(o, ...);
但概念是：使用自定义替换器，并跟踪解析的对象值。
作为es6中编写的实用函数：
// safely handles circular references
JSON.safeStringify = (obj, indent = 2) => {
let cache = [];
const retVal = JSON.stringify(
obj,
(key, value) =>
typeof value === "object" && value !== null
? cache.includes(value)
? undefined // Duplicate reference found, discard key
: cache.push(value) && value // Store value in our collection
: value,
indent
);
cache = null;
return retVal;
};
// Example:
console.log('options', JSON.safeStringify(options))
此解决方案修复了用户2451227报告的接受答案问题（当o={}；JSON.stringify（[o，o]，getCircularReplacer（）））。
函数newCircularReplacer（）{常量seenValues=[]返回循环替换器函数circleReplacer（键，值）{if（typeof value=='object'&&value！==null&&object.keys（value）.length）{常量堆栈大小=参见值长度if（堆栈大小）{for（设n=stackSize-1；参见nValues[n][key]！==value；--n）seenValues.pop（）//清除过期的引用if（参见nValues.includes（value））返回'[Circular]'}参见值push（value）}返回值}}设o={a:1}o.b=o//循环参考控制台日志(JSON.stringify（o，newCircularReplacer（））//｛a:1，b:[Circular]｝✅)o=｛｝a=[o，o]//非循环参考控制台日志(JSON.stringify（a，newCircularReplacer（））//[｛｝，｛｝]✅)
本线程中的大多数答案都是专门针对JSON.stringify使用的——它们没有显示如何实际删除原始对象树中的循环引用。（好吧，除了之后再次调用JSON.parse之外——这需要重新分配，并且会产生更高的性能影响）
要从源对象树中删除循环引用，可以使用以下函数：https://stackoverflow.com/a/63952549/2441655
然后，可以使用这些通用的循环引用移除器函数安全地调用循环引用敏感函数（如JSON.stringify）：
const objTree = {normalProp: true};
objTree.selfReference = objTree;
RemoveCircularLinks(objTree); // without this line, the JSON.stringify call errors
console.log(JSON.stringify(objTree));
我们使用对象扫描进行数据处理，这可能是一个可行的解决方案。这就是它的工作方式（也可以正确修剪数组）
.作为控制台包装｛最大高度：100%！重要；顶部：0｝<script type=“module”>导入对象扫描自'https://cdn.jsdelivr.net/npm/object-scan@18.1.2/lib/index.min.js'；const prune=（data）=>对象扫描（['**']{rtn：'计数'，filterFn：（｛isCircular，父级，属性｝）=>{if（isCircular）{if（Array.isArray（父级））{parent.splice（属性，1）；}其他{删除父项[属性]；}返回true；}return false；},breakFn:（｛isCircular｝）=>isCircular==true})（数据）；常量obj={a:'foo'，c:[0]}；obj.b=对象；obj.c.push（obj）；console.log（obj）；//=><ref*1>｛a:'foo'，c:[0，[Circular*1]]，b:[Circulal*1]｝console.log（prune（obj））；//返回循环计数// => 2console.log（obj）；//=>｛a:'foo'，c:[0]｝</script>
免责声明：我是物体扫描的作者
