When using the json.stringify method to convert a string, an error typeerror: converting circular structure to JSON will be reported

Reason: there is a circular reference to itself in the object;

For example:

let test = { a: 1, b: 2 };
test.c = test; // Circular references
JSON.stringify(test); // report an error

Solution:
the following JSON_ STR is the converted String of JSON. Stringify

var cache = [];
var json_str = JSON.stringify(json_data, function(key, value) {
    if (typeof value === 'object' && value !== null) {
        if (cache.indexOf(value) !== -1) {
            return;
        }
        cache.push(value);
    }
    return value;
});
cache = null;	//release cache