一楼给敬佩的阮老师
引入原则：
<head>
<script src='../build/react.js></script>
<script src='../build/react-dom.js></script>
<script src='../build/browser.min.js></script>
</head>
body区域
<div id='example'></div>
<script type='text/bable'>
//**our codes goes here!
</script>
实际上线用babel进行转换
bable src --out-dir build
ReactDOM.render()
示例：
ReactDOM.render(
<h1>hello world!</h1>,
document.getElementById('example');
)
JSX语法
var names =['Alice','Emily','Kate'];
ReactDOM.render(
<div>
{
names.map(function(name){
return <div>Hello,{name}!</div>
})
}
</div>,
document.getElementById('example')
);
JSX允许在模板中直接插入JavaScript变量
var arr = [
<h1>Hello world!</h1>,
<h2>React is awesome</h2>
];
ReactDOM.render(
<div>{arr}</div>,
document.getElementById('example')
);
组件
React.createClass用于生成一个组件类
var HelloMessage = React.creatClass({
render:function(){
return <h1>Hello {this.props.name}</h1>;
}
});
ReactDOM.render(
<HelloMessage name='john' />,
document.getElementById('example')
);
- 组件的第一个字母必须大写
- 组件只能包含一个顶层标签
- class属性需要写成className
this.props.children
this.props.children 表示组件所有的子节点
var NoteList = React.createClass({
render:function(){
return(
<ol>
{
React.Children.map(this.props.children,function(child){
return <li>{child}</li>
})
}
</ol>
);
}
});
ReactDOM.render(
<NoteList>
<span>hello</span>
<span>World</span>
</NoteList>,
document.body
);
使用React.Children.map来遍历子节点，不用担心this.props.children的数据类型
PropTypes
验证实例的属性是否符合要求
var MyTitle = react.createClass({
propTypes:{
title:React.PropTypes.string.isRequired,
},
render:function(){
return <h1>{this.props.title}</h1>
}
});
var data = 123;
ReactDOM.render(
<MyTitle title={data} />,
document.body
);
getDefaultProps可以用来设置组件属性的默认值
getDefaultProps:function(){
return {
title: 'Hello World'
};
}
获取真实的DOM节点
有时需要从组件中获取真实的DOM节点，需要用到ref属性。
var MyComponet = React.CreatClass({
handleClick:function(){
this.refs.myTextInput.focus();
},
render:function(){
return (
<div>
<input type='text' ref='myTextInput' />
<input type='button' value ='Focus the text input'
onClick={this.handleClick} />
</div>
);
}
});
ReactDOM.render(
<MyComponet />,
document.getElementById('example')
);
指定click事件回调函数，确保DOM真实渲染后触发，除此还支持KeyDown等事件
this.state
组件视为状态机，用户互动，状态变化，重新渲染UI。
var LikeButton = React.CreatClass({
getInitialState:function(){
return {liked:false};
},
handleClick:function(event){
this.setState({liked: !this.state.liked});
},
render:function(){
var text = this.state.liked? 'like':'haven\'t liked';
return(
<p onClicked={this.handleClick}>
You {text} this. Click to toggle.
</p>
);
}
});
ReactDom.render(
<LikeButton />,
document.body
);
this.props表示一旦定义不再更改的属性，this.state表示随用户互动产生变化的特性。
表单
var Input = React.createClass({
getInitialState:function(){
return {value:'Hello!'};
},
handleChange:function(event){
this.setState({value:event.target.value});
},
render:function(){
var value = this.state.value;
return (
<div>
<input type='text' value = {value}
onChange = {this.handleChange} />
<p>{value}</p>
</div>
);
}
});
ReactDOM.render(<Input />,document.body);
这里取得输入框的值没有使用this.props.value,选用了event.target.value。
组件的生命周期
- Mounting: 已插入真实DOM
- Updating: 正在被重新渲染
- Unmounting:已移除真实DOM
var Hello = React.createClass({
getInitialState:function()
return {
opacity:1.0
}
},
compontentDidMount:function(){
this.timer = setInterval (function() {
var opacity = this.state.opacity;
opacity -= .05;
if(opacity < 0.1){
opacity = 1.0;
}
this.setState({
opacity:opacity
});
}.bind(this),100);
},
render: function(){
return (
<div style = {{opacity:this.state.opacity}}>
Hello {{this.props.name}
</div>
);
}
});
ReactDOM.render(
<Hello name='world' />,
document.body
);
bind(this)——原生JS写法。
Ajax
使用compontentDidMount方法设置Ajax请求
var UserGist = React.createClass({
getInitialState:function(){
return {
username:'',
lastGistUrl:''
}
},
componentDidMount: function(){
$.get(this.props.source,function(result){
var lastGist = result[0];
if(this.isMounted()){
this.setState({
username:lastGist.owner.login,
lastGistUrl:lastGist.html_url
});
}
}.bind(this));
},
render:function(){
return (
<div>
{this.state.username}'s last gist is
<a href={this.state.lastGistUrl}>here</a>.
</div>
);
}
});
ReactDOM.render(
<UserGist source = 'http:xx.xxx.com' />,
document.body
);
把其他途径获取的对象传入组件
ReactDOM.render(
<RepoList promise = {$.getJSON('http://xx.xxx.com)} />,
document.body
);
var RepoList = React.createClass({
getInitialState: function(){
return { loading:true, error : null , data : null}
},
componentDidMount(){
this.props.promise.then(
value => this.setState({loading:false,data:value}),
error => this.setState({loading:false,error:error}));
},
render:function(){
if(this.state.loading){
return <span>Loading…</span>
}
else if(this.state.error !== null){
return <span>Error: {this.state.error.message}</span>;
}
else{
var repos = this.state.data.items;
var reposList = repos.map(function(repo){
return (
<li>
<a href={repo.html}>{repo.name}</a>
</li>
);
});
return (
<main>
<h1>Most Popular JavaScript Projects in Github</h1>
<ol>
{repoList}
</ol>
</main>
);
}
}
});
