kassane

Event Loop

In computer science, the event loop, message dispatcher, message loop, message pump, or run loop is a programming construct that waits for and dispatches events or messages in a program.

It works by making a request to some internal or external "event provider" (that generally blocks the request until an event has arrived), and then it calls the relevant event handler ("dispatches the event").

The event-loop may be used in conjunction with a reactor, if the event provider follows the file interface, which can be selected or 'polled' (the Unix system call, not actual polling).

The event loop almost always operates asynchronously with the message originator.

fernandohu

Reading data before application startup in Angular 2

In this demonstration I will show you how to read data in Angular2 final release before application startup. You can use it to read configuration files like you do in other languages like Java, Python, Ruby, Php.

This is how the demonstration will load data:

a) It will read an env file named 'env.json'. This file indicates what is the current working environment. Options are: 'production' and 'development';

b) It will read a config JSON file based on what is found in env file. If env is "production", the file is 'config.production.json'. If env is "development", the file is 'config.development.json'.

paulirish

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