Stringifying YAML

stringify(value: unknown): string

stringify serializes a JS value — strings, numbers, booleans, null, arrays, plain objects, and Uint8Array (emitted as !!binary) — to block-style YAML text.

import { stringify } from "lightning-yaml";

console.log(
  stringify({
    service: "api",
    replicas: 3,
    env: ["NODE_ENV=production", "PORT=8080"],
  }),
);
// service: api
// replicas: 3
// env:
//   - NODE_ENV=production
//   - PORT=8080

stringify emits block-style YAML with the conventional 2-space indent and keys in the value’s own insertion order.

Round-tripping

For JSON-shaped data, parse and stringify round-trip:

import { parse, stringify } from "lightning-yaml";

const original = `
service: api
replicas: 3
env:
  - NODE_ENV=production
  - PORT=8080
`;

const value = parse(original);
const text = stringify(value);

parse(text); // deep-equal to `value`

This holds for richer documents too — stringify emits anchors/aliases for values that share a reference (or form a cycle) rather than duplicating them, so parse(stringify(x)) reconstructs the same shared-reference graph, not a deep copy of it.

Performance

stringify is tuned for throughput, not just correctness — it approaches JSON.stringify’s speed in the sense that matters most: it stays within a single order of magnitude of it (roughly 5× the time, on record-shaped data), rather than the tens-of-times-slower results js-yaml and yaml produce on the same data, and it does so at lower peak memory than either competitor. See Benchmarks for the full head-to-head, and Allocation Strategy for why.

Next

• Parsing for the reverse direction.
• API reference for the full signatures and types.