Understanding React
React is a user interface for building JAVASCRIPT library. (JQuery is )
React mainly used to build the UI , many people think React is MVC in V (view). mvvm
React originated in Facebook internal project.
grammar:
React use JSX (JS xml) to replace the conventional JavaScript
JSX is javascript syntactic sugar
We do not necessarily use the JSX , but it has the following advantages:
1 , JSX execute faster, because it is compiled into JavaScript has been optimized code.
2 , it is type-safe, you can find errors during compilation.
3 , using JSX writing templates easier and faster.
jsx template const = TEMP < h1 of > Hello </ h1 of > ; Let A = < div > < h1 of > </ h1 of > < H2 > </ H2 > outside must be wrapped in a sub-tag root label </ div >
Use React in two ways:
1, directly in the html using-side script manner introduction Babel , REACT , reac_dom JS file
Inefficient, due to the real-time conversion
2, installation of scaffolding, in the manner of projects using react
Package.json is dependent recording project download package
installation steps:
Installation create-react-app
cnpm instal -g create-react-app // global installed scaffolding
Create a project
create-react-app app ( project name )
Startup project
cd app
npm start //yarn start
Installation cnpm
npm install -g cnpm
For use someone else's project, is generally not the nodelmodel ( put the project depends folder ) it to you (because too much), so first of all depend on good first download the project, through npm install automatically according to packge.json file the record downloading dependencies, and then you can start the project.
There are two ways of declaring components:
1, the function declaration
Function name must be capitalized, it represents a component, or the browser considered html element
The first parameter is a template ( or a react element ) , the second parameter is dom node
2, class declaration