[JSON]: make parsing lenient by default and display better errors

[vicb]

• I'd be willing to implement this feature (contributing guide)

Description

Nx uses JSON.parse

It has several pain points:

• It does not support trailing comma - while TS is happy with them i.e. when reading tsconfig.json,
• The error messages are helpless: Error in JSON at position 1234

It should be easy to switch parser.

Typescript uses https://www.npmjs.com/package/jsonc-parser (as a devDependency)

https://www.npmjs.com/package/parse-json seems to have nice error messages.

The hard part for this issue is probably to pick the right parser...

[Phillip9587]

Nx already uses jsonc-parser. I implemented the json utils in #5859.

Take a look at:

• https://nx.dev/packages/devkit/documents/index#parsejson

• https://nx.dev/packages/devkit/documents/index#serializejson

• https://nx.dev/packages/devkit/documents/index#stripjsoncomments

• https://nx.dev/packages/devkit/documents/index#readjson

• https://nx.dev/packages/devkit/documents/index#readjsonfile

• https://nx.dev/packages/devkit/documents/index#writejson

• https://nx.dev/packages/devkit/documents/index#writejsonfile

[vicb]

Oh thanks!

nx/packages/nx/src/utils/json.ts

Lines 40 to 58 in e8b2731

	export function parseJson<T extends object = any>(
	input: string,
	options?: JsonParseOptions
	): T {
	try {
	return JSON.parse(input);
	} catch {}
	const errors: ParseError[] = [];
	const result: T = parse(input, errors, options);
	if (errors.length > 0) {
	const { error, offset } = errors[0];
	throw new Error(
	`${printParseErrorCode(error)} in JSON at position ${offset}`
	);
	}
	return result;

Sorry I stopped parsing the code at return JSON.parse(input); :(

Because we already use jsonc-parser I wonder if:

• it would make sense to make parseJson lenient by default (allow comment and trailing commas),
• it woud be possible to display better error message than Error in JSON at position 1234 - it wonder if getLocation could help here.

[github-actions]

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