Stringfy，避免类型错误: 将循环结构转换为 JSON

Question

I have a big object I want to convert to JSON and send. However it has circular structure. I want to toss whatever circular references exist and send whatever can be stringified. How do I do that?

Thanks.

var obj = {
  a: "foo",
  b: obj
}

I want to stringify obj into:

{"a":"foo"}

转载于:https://stackoverflow.com/questions/11616630/json-stringify-avoid-typeerror-converting-circular-structure-to-json

Answer 1

Use JSON.stringify with a custom replacer. For example:

// Demo: Circular reference
var o = {};
o.o = o;

// Note: cache should not be re-used by repeated calls to JSON.stringify.
var cache = [];
JSON.stringify(o, function(key, value) {
    if (typeof value === 'object' && value !== null) {
        if (cache.indexOf(value) !== -1) {
            // Duplicate reference found
            try {
                // If this value does not reference a parent it can be deduped
                return JSON.parse(JSON.stringify(value));
            } catch (error) {
                // discard key if value cannot be deduped
                return;
            }
        }
        // Store value in our collection
        cache.push(value);
    }
    return value;
});
cache = null; // Enable garbage collection

The replacer in this example is not 100% correct (depending on your definition of "duplicate"). In the following case, a value is discarded:

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, ...);

But the concept stands: Use a custom replacer, and keep track of the parsed object values.