Leonardo Di Lella ledil

The issue:

..mobile browsers will wait approximately 300ms from the time that you tap the button to fire the click event. The reason for this is that the browser is waiting to see if you are actually performing a double tap.

(from a new defunct https://developers.google.com/mobile/articles/fast_buttons article)

touch-action CSS property can be used to disable this behaviour.

touch-action: manipulation The user agent may consider touches that begin on the element only for the purposes of scrolling and continuous zooming. Any additional behaviors supported by auto are out of scope for this specification.

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

	from aioredis import Channel, Redis
	from fastapi import FastAPI
	from fastapi.params import Depends
	from fastapi_plugins import depends_redis, redis_plugin
	from sse_starlette.sse import EventSourceResponse
	from starlette.responses import HTMLResponse

	html = """
	<!DOCTYPE html>
	<html>

	import uvicorn
	from aioredis import create_pool
	from fastapi import FastAPI
	from starlette.websockets import WebSocket

	app = FastAPI()


	REDIS_URL = 'redis://redis:6379'
	REDIS_DB = 0

	import { useState } from 'react';
	import axios from 'axios';

	type RequestConfig = {
	url?: string;
	baseURL?: string;
	initialIsLoading?: boolean;
	withCredentials?: boolean;
	onSuccess?: Function;
	onError?: Function;

	function State() {
	this.actions = {};
	this.subscriptions = [];
	this.history = [];
	}

	State.prototype.subscribe = function(element, action, callback) {
	this.subscriptions[action] = this.subscriptions[action] \|\| [];
	this.subscriptions[action].push(function(data) {
	callback.apply(element, data);

	global
	log /dev/log local0
	log /dev/log local1 notice
	chroot /var/lib/haproxy
	stats socket /run/haproxy/admin.sock mode 660 level admin
	stats timeout 30s
	user haproxy
	group haproxy
	daemon
	maxconn 2048

	import math


	def calculate_polygons(startx, starty, endx, endy, radius):
	"""
	Calculate a grid of hexagon coordinates of the given radius
	given lower-left and upper-right coordinates
	Returns a list of lists containing 6 tuples of x, y point coordinates
	These can be used to construct valid regular hexagonal polygons

	class MultiFormMixin(ContextMixin):

	form_classes = {}
	prefixes = {}
	success_urls = {}
	grouped_forms = {}

	initial = {}
	prefix = None
	success_url = None

	def track_field_changes(only=None, exclude=()):
	"""
	Django models decorator for tracking fields changes

	:only: fields to track for changes (all otherwise)
	:exclude: fields to exclude from tracking

	Adds to model instance:
	get_old_value(field_name) — old value of given field
	is_changed(field_name=None) — is any field (or given field) is changed