JSON5

JSON5 extends JSON with the parts of JavaScript's object syntax people write by hand: unquoted keys, single-quoted strings, comments, trailing commas, hex numbers and Infinity. JSON5 in runtime:serialization reads it, writes it, and changes a value in it without disturbing the rest of the file. The exact rules are in the API reference.

Reading JSON5

JavaScript

import { JSON5 } from "runtime:serialization";
import { file } from "runtime:fs";

const config = JSON5.parse(await file("renovate.json5").text());
console.log(config.extends); // ["config:recommended"]

JSON5

{
  // renovate.json5
  extends: ['config:recommended'],
  prHourlyLimit: 0x2,
  schedule: ['before 6am on monday',],
}

For the JSON it shares, JSON5.parse returns what JSON.parse would, and it takes the same reviver argument. A file that is not JSON5 throws a SyntaxError with its line and column; JSON5.validate checks a file without reading it into a value.

Writing JSON5

JSON5.stringify takes the same arguments as JSON.stringify and writes JSON5: keys without quotes where they are plain identifiers, Infinity and NaN as themselves, and each string in the quote that needs fewer escapes.

JavaScript

JSON5.stringify({ name: "app", limit: Infinity, tags: ["it's"] }, null, 2);
// {
//   name: 'app',
//   limit: Infinity,
//   tags: [
//     "it's",
//   ],
// }

Pass { quote: '"' } instead of the replacer to choose one quote for every string: JSON5.stringify(value, { quote: '"', space: 2 }).

Updating a file

JSON5.edit returns the text with one value changed and every other byte kept, comments included. The new value is written in the file's own style: its quotes, its indentation, and its trailing commas.

JavaScript

import { JSON5 } from "runtime:serialization";
import { file, write } from "runtime:fs";

const text = await file("renovate.json5").text();
await write("renovate.json5", JSON5.edit(text, ["automerge"], true));

Pass undefined as the value to remove a key.