@crescendolab/parse-json

A user-friendly wrapper for JSON.parse().

``ts
// ✅ Returns type JsonValue which is stricter than unknown.
// ✅ Fallback specified value is returned if input is not a valid JSON string.
const output = parseJson(input, null);
// ^? const output: JsonValue
if (typeof output === "function") {
output;
// ^? const output: never
}
if (output === undefined) {
output;
// ^? const output: never
}

// ❌ Return with type any.
// ❌ Might throw an error if input is not a valid JSON string.
const vanillaOutput = JSON.parse(input);
// ^? const vanillaOutput: any
`

Installation

`sh
pnpm i @crescendolab/parse-json
`

Usage

`ts
import { parseJson } from "@crescendolab/parse-json";

const input = await loadJson();
const output = parseJson(input);
`

Options

`ts
parseJson(input, options);
`

$3

- Type: any

Specify a fallback value to be returned if it fails to parse input as a JSON string.

`ts
const input = "not a valid json string";

// ✅ Get undefined instead of throwing an error.
const output = parseJson(input, { fallback: undefined });
`

$3

- Type: (input: string) => JsonValue

Specify a custom parser function.

For example, you can use json5 for comments in json or parse-json for helpful error messages.

`ts
import { parseJson } from "@crescendolab/parse-json";
import json5 from "json5";

const input = {
// This is a comment
"foo": "bar"
};

// ✅ This will not throw an error.
const output = parseJson(input, {
parser: json5.parse,
});
`

Create your own parser

You can create a parser with a custom default options where the options are the same as the options argument of parseJson().

`ts
import { parseJson } from "@crescendolab/parse-json";

const myParser = parseJson.create(options);
const myParser = parseJson.create({ fallback: undefined });
``

License

MIT © Crescendo lab