Add a feature to create a final used/unused selector report

[paceaux]

There should be more information added to the CLI, and the pages.json, about which selectors are ultimately used/unused.

I wrote a separate js file for determining this, but it would be nice if this were a core feature.

This is what I wrote that generally works.

const fs = require('fs');

if (process.argv.length <= 2) {
	console.error('needed name of file');
	process.exit(1);
}

const fileName = process.argv[2];
const outputFileName = fileName.replace('.pages.json', ''); 


function getResultsData(fileName) {
		if (!fileName) return null;

		try {
			const file = fs.readFileSync(fileName, 'utf8');
			const fileData = JSON.parse(file);

			return fileData;
		} catch (fileError) {
			console.error(fileError);
		}
}

function filterUsedAndUnused(pagesWithSelector) {
	if (!pagesWithSelector) throw new Error('not an object');
	const unusedSet = new Set();
	const usedSet = new Set();

	pagesWithSelector.forEach(page => {
		const { unusedSelectors, usedSelectors} = page;
		unusedSelectors.forEach(unusedSelector => unusedSet.add(unusedSelector));
		usedSelectors.forEach(usedSelector => usedSet.add(usedSelector));
	});

	unusedSet.forEach((selector) => {
		if (usedSet.has(selector)) {
			unusedSet.delete(selector);
		}
	});

	return {unusedSet, usedSet}; 
}


function outputFile(data) {
	const json = JSON.stringify(data, null, 2);
	try {
		fs.writeFile(`${outputFileName}.filtered.json`, json, writeError => {
			if (writeError) {
				console.error(writeError)
			}
		})
	} catch (outputErr) {
		console.error(outputErr);
	}
}
try {
	const searchResults = getResultsData(fileName);
	const { pagesWithSelector } = searchResults;
	const {unusedSet, usedSet} = filterUsedAndUnused(pagesWithSelector);

const convertedUsed = [...usedSet];
const convertedUnused = [...unusedSet];
const totalUsedSize = convertedUsed.length;
const totalUnusedSize = convertedUnused.length;

const results = {
	totalUsed : totalUsedSize,
	totalUnused : totalUnusedSize,
	totalSelectors : totalUsedSize + totalUnusedSize,
	used: convertedUsed,
	unused: convertedUnused
};

outputFile(results);

	console.log(`\n=====UNUSED: ${totalUnusedSize}=====`);
	console.log(unusedSet);
	console.log(`\n=====USED: ${totalUsedSize}=====`);
	console.log(usedSet);



} catch (readErr) {
	console.error(readError);
}

[paceaux]

Note: this could be a "report" flag, in case we wanted to add other summarizing / learning that comes after the pages.json is generated.

Reporting could include:

• list of used/unused selectors
• list of pages with matches
• element details?