TypeError: cyclic object value - JavaScript 编辑
The JavaScript exception "cyclic object value" occurs when object references were found in JSON. JSON.stringify()
doesn't try to solve them and fails accordingly.
Message
TypeError: cyclic object value (Firefox) TypeError: Converting circular structure to JSON (Chrome and Opera) TypeError: Circular reference in value argument not supported (Edge)
Error type
What went wrong?
The JSON format per se doesn't support object references (although an IETF draft exists), hence JSON.stringify()
doesn't try to solve them and fails accordingly.
Examples
Circular references
In a circular structure like the following
var circularReference = {otherData: 123};
circularReference.myself = circularReference;
JSON.stringify()
will fail
JSON.stringify(circularReference);
// TypeError: cyclic object value
To serialize circular references you can use a library that supports them (e.g. cycle.js) or implement a solution by yourself, which will require finding and replacing (or removing) the cyclic references by serializable values.
The snippet below illustrates how to find and filter (thus causing data loss) a cyclic reference by using the replacer
parameter of JSON.stringify()
:
const getCircularReplacer = () => {
const seen = new WeakSet();
return (key, value) => {
if (typeof value === "object" && value !== null) {
if (seen.has(value)) {
return;
}
seen.add(value);
}
return value;
};
};
JSON.stringify(circularReference, getCircularReplacer());
// {"otherData":123}
See also
JSON.stringify
- cycle.js – Introduces two functions,
JSON.decycle
andJSON.retrocycle
, which makes it possible to encode and decode cyclical structures and dags into an extended and retrocompatible JSON format.
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