React知识点总结
Render Props
Render Props目的是达到组件的状态复用,通过props传一个函数给组件A,该函数返回一个组件B,这样在组件A里面就可以渲染组件B了(使用的是组件A中的state)。
一、Render Props使用
class Cat extends React.Component {
render() {
const mouse = this.props.mouse;
return (
<img src="/cat.jpg" style={
{
position: 'absolute', left: mouse.x, top: mouse.y }} />
);
}
}
class Mouse extends React.Component {
constructor(props) {
super(props);
this.handleMouseMove = this.handleMouseMove.bind(this);
this.state = {
x: 0, y: 0 };
}
handleMouseMove(event) {
this.setState({
x: event.clientX,
y: event.clientY
});
}
render() {
return (
<div style={
{
height: '100vh' }} onMouseMove={
this.handleMouseMove}>
{
/*
Instead of providing a static representation of what <Mouse> renders,
use the `render` prop to dynamically determine what to render.
*/}
{
this.props.render(this.state)}
</div>
);
}
}
class MouseTracker extends React.Component {
render() {
return (
<div>
<h1>移动鼠标!</h1>
<Mouse render={
mouse => (
<Cat mouse={
mouse} />
)}/>
</div>
);
}
}
二、JSX的本质
JSX
是React.createElement()
的语法糖,Babel 会把 JSX 转译成 React.createElement()
函数调用,将JSX编译成JS代码。