minifyfromhtml/minifyfromhtml.js

let argv = require('minimist')(process.argv.slice(2));
let fs = require('fs');
let path = require('path');
let jsdom = require('jsdom');
let JSDOM = jsdom.JSDOM;
let minify = require('minify');

process.on('unhandledRejection', up => { throw up; });

let usage = `usage:
	minifyfromhtml --js=<output js file> --css=<output css file> --exclude=<exclude files> < <input file>

	the minification process uses minify under the hood.
	http://coderaiser.github.io/minify/

	example:
	minifyfromhtml --js=dist/mywidget.min.js --css=dist/mywidget.min.css --exclude=js/jquery.js < example/index.html
`;

if (argv.h) {
	console.log(usage);
	process.exit(0);
}

if (!argv.js && !argv.css) {
	console.log(usage);
	process.exit(0);
}

let excludeFiles = argv.exclude || [];
if (typeof(excludeFiles) === 'string') {
	excludeFiles = [excludeFiles];
}

let readStdin = function(cb) {
	let stdin = '';
	process.stdin.resume();
	process.stdin.setEncoding('utf-8');
	process.stdin.on('data', function(buf) {
		stdin += buf;
	});
	process.stdin.on('end', function() {
		cb(stdin);
	});
};


readStdin(function(html) {
	let dom = new JSDOM(html);
	let getTagAttrs = function(dom, tag, attr, filter) {
		let elements = [];

		let document = dom.window.document;
		let elementTags = document.getElementsByTagName(tag);
		let i = elementTags.length;
		for (let i = 0; i < elementTags.length; i++) {
			if (!filter ||
				(filter && elementTags[i].getAttribute(Object.keys(filter)[0]) === filter[Object.keys(filter)[0]])) {
				let src = elementTags[i].getAttribute(attr);
				if (src) {
					elements.push(src);
				}
			}
		}
		return elements;
	};


	let processThings = function(things, outFile) {
		//remove exluded
		excludeFiles.forEach(i => {
			let index = things.indexOf(i);
			if (index !== -1) {
				things.splice(index, 1);
			}
		});

		let processedThings = {};
		for (let i = 0; i < things.length; i++) {
			let thing = things[i];

			minify(thing)
			.then(function(data) {
				processedThings[thing] = data;

				if (Object.keys(processedThings).length === things.length) {
					//write things

					//clear out dist file
					fs.writeFileSync(outFile, '');

					//write files
					for (let i = 0; i < things.length; i++) {
						const thing = things[i];

						console.log(thing + ' -> ' + outFile);
						fs.appendFileSync(outFile, processedThings[thing] + '\n');
					}
				}
			});
		}
	};

	if (argv.js) {
		processThings(getTagAttrs(dom, 'script', 'src'), argv.js);
	}

	if (argv.css) {
		processThings(getTagAttrs(dom, 'link', 'href', {rel: 'stylesheet'}), argv.css);
	}
});