Epic React

learnt how we can have empty body and still insert Hello world inside doc

learnt imperative vs declarative

• SQL - declarative - just tells what I want not "how" to get it
• pure js - imperative, react - declarative
• many declarative approaches have some sort of underlying abstractions
• Programming languages - imperative: C, C++, Java - Declarative: SQL, HTM - mix: Javascript, Python
• React helps us create declarative UI
• declarative code is program that can be context-independent (same code can be used in different programs)
• functional programming is a subset of declarative programming

react - create react elements (like document.createElement()) -> React.createElement

reactDOM - render react elements to DOM (like rootElement.append())-> ReactDOM.render

you need babel to convert JSX to React APIs

• see conversion at babel↗ (opens babeljs.io in a new tab)

understood what are react elements (objects that define how it should look on screen)

React.createElement, first argument can be a function

{{}} = JSX expression + object expression

• filter, map, reduce

• foreach