JSON

The JSON functions produce a tree of plain objects instead of JavaScript. fromJSON rebuilds the value from the tree without running any code from the sender. This makes the JSON form the right choice whenever the receiver does not trust the sender, such as a server that reads a request body.

import { fromJSON, toJSON } from 'seroval';

const tree = toJSON({ when: new Date('2026-01-01'), ids: new Set([1, 2]) });
const body = JSON.stringify(tree);

const value = fromJSON(JSON.parse(body));
value.ids.has(2); // true

#Functions

toJSON and toJSONAsync take the same options as serialize.

The tree has three fields: t holds the value, f holds the features the sender used, and m lists the values that are referenced more than once. Treat the format as opaque. It is meant to be produced by toJSON and read by fromJSON.

#fromJSON options

The sender's f field decides which features the tree may use. disabledFeatures is how the receiver turns features off, whatever the sender says. If you do not need RegExp, disable it:

import { Feature, fromJSON } from 'seroval';

fromJSON(tree, { disabledFeatures: Feature.RegExp });

#compileJSON

compileJSON converts a tree into the same JavaScript that serialize produces. This lets you build the tree once, then decide later whether to send it as JSON or as JavaScript.

#Cross-reference JSON

toCrossJSON, toCrossJSONAsync and toCrossJSONStream produce the JSON form of the cross-reference functions. Decode their output with fromCrossJSON, or with createCrossDeserializer for a stream. See Streaming.