benfluleck

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()

benfluleck

I heard some points of criticism to how React deals with reactivity and it's focus on "purity". It's interesting because there are really two approaches evolving. There's a mutable + change tracking approach and there's an immutability + referential equality testing approach. It's difficult to mix and match them when you build new features on top. So that's why React has been pushing a bit harder on immutability lately to be able to build on top of it. Both have various tradeoffs but others are doing good research in other areas, so we've decided to focus on this direction and see where it leads us.

I did want to address a few points that I didn't see get enough consideration around the tradeoffs. So here's a small brain dump.

"Compiled output results in smaller apps" - E.g. Svelte apps start smaller but the compiler output is 3-4x larger per component than the equivalent VDOM approach. This is mostly due to the code that is usually shared in the VDOM "VM" needs to be inlined into each component. The tr

benfluleck

import React from 'react'
import Text from '<atoms>/Text/Text'
import { useState } from 'react'


export const useForm = (initialValues) => {

  const [values, setValues] = useState(initialValues)

benfluleck

var express = require('express');
var app = express();
var fs = require('fs');
var https = require('https');

var key = fs.readFileSync('key.pem');
var cert = fs.readFileSync( 'cert.pem' );

benfluleck

// BAD

class InventoryRequester {
  constructor() {
    this.REQ_METHODS = ['HTTP'];
  }

  requestItem(item) {
    // ...
  }

benfluleck

// bad
class Post {
  constructor(){
  }
  
  editPost(){
    console.log('Post edited')
  }
  
  createPost(){

benfluleck

// bad
class Bird{
  fly(){
    console.log('I can fly')
  }
}
class Duck extends Bird {
  constructor(){
    super();
  

benfluleck

// Bad
class Bird{}
class FlyingBird extends Bird {
  constructor(type, name){
    super();
    this.name = name
  } 
  flightSpeed(){
    if(this.name === "parrot" || this.name === "dove"){
      return ('I can fly medium-fast')

benfluleck

// Bad Case
class Staff {
  constructor(staff) {
    this.staff = staff;
  }

  registerStaff(staff) {
    if (this.validateUser(staff)) {
      return `${staff} has been created`;
    }

benfluleck

function Node(value){
  this.value = value
  this.left = null;
  this.right = null;
}

Node.prototype.toString = function() {
  return this.value;
}