Recat.js-JS Tutorial-php.cn

0. Preface

"As time goes by in a hurry, I only care about you." Recently, I haven't updated the article very much. I hope you won't be offended, haha! Recently, the company is working on the recat.js project. However, I am not very familiar with it. I am also a novice and am still learning. However, if you have any good learning documents, you can leave them to me. Thank you all.

Recat.js

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Introduction

React is a JAVASCRIPT library for building user interfaces.

2. Features

Declarative design −React adopts a declarative paradigm, which can easily describe applications.
Efficient −React minimizes interaction with the DOM by simulating the DOM.
Flexible −React plays well with known libraries or
frameworks.
JSX − JSX is an extension of JavaScript syntax. JSX is not required for React development, but it is recommended.
Component − Building components through React makes it easier to reuse code and can be well applied in the development of large projects.
One-way response data flow − React implements one-way response data flow, thereby reducing duplicate code, which is why it is better than traditional
Data binding simpler.

3. Key points

Before talking about the code, I would like to say a few more important points:

You need to import several files, the order cannot be changed

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pass value
, bindeventwait
routing

1. First introduce a few files under the title

<script src="../bower_components/react/react.min.js"></script>
<script src="../bower_components/react/react-dom.min.js"></script>
<script src="../lib/browser.min.js"></script>

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2. The type of code

 <p id="demo"></p>

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4. js code

 <script type="text/babel">
        class Hello extends  React.Component{
            getDate(){
                return new Date-0;
            }
            render(){
                var name = this.getDate();
                return (
                    <p>
                        <p>123</p>
                        <p>hello,{this.getDate()}</p>
                        <input type="text"/>
                    </p>
                )
            }
        }

        ReactDOM.render(
                <Hello/>,
                document.getElementById('demo')
        )
    </script>

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In addition to the native HTML p tags we have written, we can customize tags in recat, which does not represent a real

DOM node

. From the perspective of recat, it is just an instance of recat Components. So how do these recat Components appear on the page? It is to call the render() method in recat. The first parameter is the recat Components we want to render. The second parameter The parameter Components is the container element at the position to be inserted after rendering. In summary, the rendering result of hello is inserted into the element container with the ID of demo. Then let’s take a look at the rendering result

Recat.js
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Then let’s take a look at the rendering result Page structure

Recat.js
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So now let’s see if everything I said has been reflected, and That p for data-recatroot, we don’t seem to have named this

attribute
. This is something recat does internally for you, because I am also a beginner and don’t quite understand it. Of course, if you know it, you can tell me. How to add some styles, you can also add them like this.

5. HTML structure code

Yes, you guessed it, it’s still this structure code, a simple container

 <p id="demo"></p>

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6. CSS代码

在这里我设置的是我在recat 那个render()方法里的一个className的p，为什么叫className，因为class是js里的保留字，所以我们得用className这个属性，而且我们这样写也是设置样式的一种方式。

 <style type="text/css">
        .demo{
            font-size: 50px;
        }
    </style>

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7. js代码

下面你要注意我写的render()方法里的东西，还有另外一种设置样式的方式，那就是设置内联样式，为什么不直接设置fontSize:50,backgroundColor:'red',color:'#fff'”？因为recat这里不支持是字符串的形式，要写一个对象，key和value这样的方式，它才可以解析。

<script type="text/babel">
        class Hello extends  React.Component{

            render(){
                var name = "刘玉森";
                var style={fontSize:50,backgroundColor:'red',color:'#fff'};

                return (
                    <p>
                        <p className="demo">123</p>
                        <p style={style}>hello,{name}</p>
                        <input type="text"/>
                    </p>
                )
            }
        }

        ReactDOM.render(
                <Hello/>,
                document.getElementById('demo')
        )
    </script>

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展示出来之后的结果

Recat.js

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props在recat中是很重要的一个方法

Recat.js

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8. HTML容器

这里呢容器没有变，还是那个容器

<p id="demo"></p>

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9. js代码

<script type="text/babel">
    class Hello extends  React.Component{

        render(){
            return (
                <p>
                    <p>123</p>
                    <p>hello,{this.props.name}</p>
                </p>
            )
        }
    }
    class Hello1 extends  React.Component{

        render(){
            return (
                <p>
                    <p>123</p>
                    <p>hello,{this.props.address}</p>
                </p>
            )
        }
    }

    class Parent extends  React.Component{
        render(){
            return (
                <p>
                    <Hello name={this.props.name}/>
                    <Hello1 address={this.props.address}/>
                </p>
            )
        }
    }

    ReactDOM.render(
            <Parent name="刘玉森"  address="110"/>,
            document.getElementById('demo')
    )
</script>

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这里呢我就得大家说一下我的那个代码，首先呢，我先自定义了一个parent这个标签，然后我创建了一个parent这个组件，我利用this.props把组件外向组件内传值，然后我再创建俩个hello，hello1的组件，获取父元素parent里的值。

看一下页面渲染之后的效果

Recat.js

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再看一下页面渲染之后的页面结构

Recat.js

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10.HTML代码

依然还是这个容器

<p id="demo"></p>

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11. js代码

<script type="text/babel" >
    class Hello extends  React.Component{

        render(){
            return (
                <ul>
                    <li>00000000</li>
                    {
                        this.props.children.map(function(item){
                            return <li>{item}</li>;
                        })
                    }
                </ul>
            )
        }
    }


    ReactDOM.render(
        <Hello>
        <p>11111111</p>
        <p>22222222</p>
        <p>33333333</p>
        <p>44444444</p>
        </Hello>,
        document.getElementById('demo')
    )
</script>

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这里呢，我们先写一个li跟我们循环遍历出来的li做个鲜明的对比，这里就利用this.props.children这个方法来读取组件内部的子标签，可以该数组进行遍历

那么我们看下渲染之后的结果

Recat.js

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还有我们渲染之后的页面结构

Recat.js

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12. HTML代码

容器......

 <p id="demo"></p>

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13. js文件

先写一个我遇到的坑

<script type="text/babel" >
    class Hello extends  React.Component{
        getDefaultProps(){
            return {
                name : "刘玉森"
            };
        }
        render(){
            return (
                <h1> hello,{this.props.name}</h1>
            )
        }
    }

    ReactDOM.render(
        <Hello/>,
        document.getElementById('demo')
    )
</script>

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这样定义组件你会发现，它不显示，因为使用 Component 定义的组件不能这样去设置默认值

看一下显示的结果

Recat.js

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是吧，它不显示，我也是醉了！！！

下面就演示一下正确的写法，下面是见证奇迹的时刻了！

<script type="text/babel" >
    class Hello extends  React.Component{

        render(){
            return (
                <h1> hello,{this.props.name}</h1>
            )
        }
    }

    Hello.defaultProps = {
        name : "刘玉森"
    }

    ReactDOM.render(
        <Hello/>,
        document.getElementById('demo')
    )
</script>

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实践是检验真理的唯一标准，来啊互相伤害啊！看图说话

Recat.js

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厉害了，我的哥！就想问还有谁，低调啊，这也是我试出来的,慢慢摸索来的...

14. HTML文件

容器还是容器

<p id="demo"></p>

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在recat里面我们添加一些事件怎么做到呢？

15. js文件

 <script type="text/babel">
        class Hello extends  React.Component{
            clkFunc(){
                alert('Hello');
            }
            render(){

                return (
                    <p>
                        <button onClick={this.clkFunc.bind(this)}>点我</button>
                    </p>
                )
            }
        }
        ReactDOM.render(
                <Hello />,
                document.getElementById('demo')
        )
    </script>

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bind这个方法，它是es5里的方法，可以改变this的指向，详细请你自己查询一下，我解释的不是太好。

那么看一下渲染页面之后的结果

Recat.js

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ref标签的属性，可以从组件中获取真实的DOM节点，也可以绑定事件

Recat.js

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16. HTML代码

容器...

<p id="demo"></p>

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17. js代码

<script type="text/babel">
        class Hello extends  React.Component{
            clkFunc(){
                this.refs.iptText.value = "hello,刘玉森";
            }
            render(){

                return (
                    <p>
                        <input ref="iptText" />
                        <button onClick={this.clkFunc.bind(this)}>点我</button>
                    </p>
                )
            }
        }


        ReactDOM.render(
                <Hello />,
                document.getElementById('demo')
        )
    </script>

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看一下渲染之后的结果

Recat.js

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通过ref这个标签的属性来绑定标签，在添加一个点击事件，调用clkFunc这个函数执行里面的语句，然后把值传入input框内，渲染页面。

下面说一下recat的生命周期，在创建到销毁的生命周期，状态和属性在生命周期中是如何流转的？那么首先要了解recat在浏览器中存在的三个状态，分别是mounted、update、unmounted，代表的含义是安装(实例化)、更新(存在期)、销毁(清理)。

Recat.js

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mouted 是指recat components被render这个方法解析生成对应的DOM节点并插入浏览器的DOM结构的一个过程。
update 是指一个mounted的recat components被重新的render的过程
unmounted 是指一个mounted的recat components对应的DOM节点被从DOM结构中移除的这样一个过程
每一个状态recat都封装了对应的hook函数，翻译成中文就是“钩子函数”，WINDOW的消息处理机制为了能在应用程序中监控系统的各种事件消息，提供了挂接各种反调函数(HOOK)的功能。

如果让我们自己封装这样的hook函数，怎么设计封装？相信大多是人都i知道will和did，将要怎么怎么样和已经怎么怎么样，将要mounted、update、unmounted，和已经mounted、update、unmounted，事实上recat的设计思想也是如此，只不过人家比我们想的更加全面一些，更详细一些，那么来一张图片吧

Recat.js

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18. HTML代码

上容器

<p id="demo"></p>

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19. js代码

 <script type="text/babel">
        class Hello extends React.Component{
            constructor(props){
                super(props);
                this.state = {
                    opacity:0.1
                }
            }
            componentDidMount(){
                this.timer = setInterval(function(){
                    var opacity = this.state.opacity;
                    opacity -=0.05;
                    if(opacity<0.1){
                        opacity=1
                    }
                    this.setState({
                        opacity:opacity
                    })

                }.bind(this),100)
            }
            render(){
                return (
                        <p style={{opacity:this.state.opacity,fontSize:50}}>
                            这个是测试react的生命周期
                        </p>
                )
            }
        }

        ReactDOM.render(
                <Hello/>,
                document.getElementById('demo')
        )
    </script>

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这里我们可以调用两个函数，componentWillMount和componentDidMount的两个方法，这两个函数的区别是componentWillMount在mounting前被调用，componentDidMount在mounted后被调用，然后测试一下recat的生命周期

看一下渲染之后的页面效果是什么样的

Recat.js

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刚才的代码中我有用到state这个方法，这个解释就是说，recat把组件看成状态机getInitialState，设置默认值，setState()可以修改state的值，每次state的值发生改变的时候，都会重新渲染UI

Recat.js

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20. HTML代码

这是这个文件的最后一个容器...

<p id="demo"></p>

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21. js文件

 <script type="text/babel">
        class Hello extends  React.Component{
            constructor(props){
                super(props);
                this.state = {
                    name:'刘玉森',
                    address:'北京',
                }
            }
            clkFunc(){

                this.setState({
                    name:'liuyusen',
                    address:'BeJing'
                })

            }
            render(){

                return (
                    <p>
                        <p>hello,{this.state.name},{this.state.address}!!!</p>
                        <button onClick={this.clkFunc.bind(this)}>点我</button>
                    </p>
                )
            }
        }



        ReactDOM.render(
                <Hello />,
                document.getElementById('demo')
        )
    </script>

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这里我有一个点击按钮，当我点击按钮的时候，改变state的值，props和state差别，props一般情况下我们通过组建调用方，在调用组件的时候指定的，props一旦指定了在一般情况下是不会改变的，而state是私属于当前组件的，state的值是可变的，正所谓“props是专情的，state是花心的”，怎么样修改state的值呢？那么就要用到setState这个方法来修改state的值。

看一下刚才的代码渲染之后的页面效果

Recat.js

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5. Conclusion

I know that the article I wrote may not be very good, and there may be many problems. Of course, I also need your guidance. Finally, I hope that the article I wrote can bring help to everyone! ! !

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