applyReviver.js 1.8 KB
/**
 * Applies the JSON.parse reviver algorithm as defined in the ECMA-262 spec,
 * in section 24.5.1.1 "Runtime Semantics: InternalizeJSONProperty" of the
 * 2021 edition: https://tc39.es/ecma262/#sec-json.parse
 *
 * Includes extensions for handling Map and Set objects.
 */
function applyReviver(reviver, obj, key, val) {
    if (val && typeof val === 'object') {
        if (Array.isArray(val)) {
            for (let i = 0, len = val.length; i < len; ++i) {
                const v0 = val[i];
                const v1 = applyReviver(reviver, val, String(i), v0);
                if (v1 === undefined)
                    delete val[i];
                else if (v1 !== v0)
                    val[i] = v1;
            }
        }
        else if (val instanceof Map) {
            for (const k of Array.from(val.keys())) {
                const v0 = val.get(k);
                const v1 = applyReviver(reviver, val, k, v0);
                if (v1 === undefined)
                    val.delete(k);
                else if (v1 !== v0)
                    val.set(k, v1);
            }
        }
        else if (val instanceof Set) {
            for (const v0 of Array.from(val)) {
                const v1 = applyReviver(reviver, val, v0, v0);
                if (v1 === undefined)
                    val.delete(v0);
                else if (v1 !== v0) {
                    val.delete(v0);
                    val.add(v1);
                }
            }
        }
        else {
            for (const [k, v0] of Object.entries(val)) {
                const v1 = applyReviver(reviver, val, k, v0);
                if (v1 === undefined)
                    delete val[k];
                else if (v1 !== v0)
                    val[k] = v1;
            }
        }
    }
    return reviver.call(obj, key, val);
}

export { applyReviver };