Kamran sodapng

Создание разметки при помощи JS

Перед чтением

Перед чтением убедитесь, что вам знакомы следующие концепции:

[DOM]
[Functions]
[Classes]
[OOP]

Pure ESM package

The package that linked you here is now pure ESM. It cannot be require()'d from CommonJS.

This means you have the following choices:

Use ESM yourself. (preferred)
Use import foo from 'foo' instead of const foo = require('foo') to import the package. You also need to put "type": "module" in your package.json and more. Follow the below guide.
If the package is used in an async context, you could use await import(…) from CommonJS instead of require(…).
Stay on the existing version of the package until you can move to ESM.

Why using the `children` prop makes `React.memo()` not work

I've recently ran into a pitfall of [React.memo()][memo] that seems generally overlooked; skimming over the top results in Google just finds it mentioned in passing in a [React issue][regit], but not in the [FAQ] or API [overview][react-api], and not in the articles that set out to explain React.memo() (at least the ones I looked at). The issue is specifically that nesting children defeats memoization, unless the children are just plain text. To give a simplified code example:

const Memoized = React.memo(({ children }) => (<div>{children}</div>));
// Won't ever re-render
<Memoized>bar</Memoized>
// Will re-render every time; the memoization does nothing

Do not use forEach with async-await

TLDR: Use for...of instead of forEach() in asynchronous code.

For legacy browsers, use for(...;...;...) or [].reduce()

To execute the promises in parallel, use Promise.all([].map(...))

The problem

Based on https://stackoverflow.com/a/31632215/761771

const reduceOp = function(args, reducer){
  args = Array.from(args);
  args.pop(); // => options
  var first = args.shift();
  return args.reduce(reducer, first);
};

DOM Performance

How the browser renders the document
- Receives the data (bytes) from the server.
- Parses and converts into tokens (<, TagName, Attribute, AttributeValue, >).
- Turns tokens into nodes.
- Turns nodes into the DOM tree.
Builds CSSOM tree from the css rules.

Про токены, JSON Web Tokens (JWT), аутентификацию и авторизацию. Token-Based Authentication

Last major update: 25.08.2020

Что такое авторизация/аутентификация
Где хранить токены
Как ставить куки ?
Процесс логина
Процесс рефреш токенов
Кража токенов/Механизм контроля токенов

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.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

	class Spiderman {
	lookOut() {
	alert('My Spider-Sense is tingling.');
	}
	}

	let miles = new Spiderman();
	miles.lookOut();

	/**
	* Event loop.
	*
	* Read details here:
	* http://dmitrysoshnikov.com/ecmascript/javascript-the-core-2nd-edition/#job
	*
	* by Dmitry Soshnikov <[email protected]>
	*/

	/**