Is there any documentation for the JSON API?

[ForbesLindesay]

I'm trying to write an alternative renderer for flow errors by parsing the output of running flow --json. Is there any documentation that tells me all the possible combinations of properties/values that might be output as errors when in JSON mode?

[ForbesLindesay]

It looks like the relevant code is https://github.com/facebook/flow/blob/a171734c02484be93996081d9e3c7742fdbf7834/src/common/errors.ml I'm unfortunately not used to reading ml, so converting this into a flow definition for the JSON output might be a challenge.

[ForbesLindesay]

I had a go at automatically generating a flow type based on the output of all the flow test cases, and got https://gist.github.com/ForbesLindesay/630fc2bf122a68e72f4f166daa9b8bd4

[ForbesLindesay]

I've just realised I can mostly just copy what the website does in

flow/website/_assets/js/tryFlow.js.es6

Lines 34 to 82 in 7e1c37a

	function printError(err, editor) {
	const clickHandler = (msg) => {
	editor.getDoc().setSelection(
	{line: msg.loc.start.line - 1, ch: msg.loc.start.column - 1},
	{line: msg.loc.end.line - 1, ch: msg.loc.end.column}
	);
	editor.focus();
	};
	return err.message.reduce((container, msg) => {
	if (msg.loc && msg.context != null) {
	const div = document.createElement('div');
	const filename = msg.loc.source !== '-' ? `${msg.loc.source}:` : '';
	const prefix = `${filename}${msg.loc.start.line}: `;
	const before = msg.context.slice(0, msg.loc.start.column - 1);
	const highlight = (msg.loc.start.line === msg.loc.end.line) ?
	msg.context.slice(msg.loc.start.column - 1, msg.loc.end.column) :
	msg.context.slice(msg.loc.start.column - 1);
	const after = (msg.loc.start.line === msg.loc.end.line) ?
	msg.context.slice(msg.loc.end.column) :
	'';
	div.appendChild(document.createTextNode(prefix + before));
	const bold = document.createElement('strong');
	bold.className = "msgHighlight";
	bold.appendChild(document.createTextNode(highlight));
	div.appendChild(bold);
	div.appendChild(document.createTextNode(after));
	container.appendChild(div);
	const offset = msg.loc.start.column + prefix.length - 1;
	const arrow = `${(prefix + before).replace(/[^ ]/g, ' ')}^ `;
	container.appendChild(document.createTextNode(arrow));
	const span = document.createElement('span');
	span.className = "msgType";
	span.appendChild(document.createTextNode(msg.descr));
	container.appendChild(span);
	const handler = clickHandler.bind(null, msg);
	bold.addEventListener('click', handler);
	span.addEventListener('click', handler);
	} else {
	const descr = `. ${msg.descr}\n`;
	container.appendChild(document.createTextNode(descr));
	}
	return container;
	}, document.createElement('li'));
	}