域名解析完成网站怎么做seo搜索方法
一、表单元素
像<input>、<textarea>、<option>这样的表单元素不同于其他元素，因为他们可以通过用户交互发生变化。这些元素提供的界面使响应用户交互的表单数据处理更加容易
交互属性，用户对一下元素交互时通过onChange回调函数来监听组件变化。表单元素支持几个受用户交互影响的属性：
value用于<input>、<textarea>
checked用于<checkbox>、<radio>
selected用于<option>
二、受限组件和不受限组件
1.受限组件与双向数据绑定
受限组件：设置了value的<input>是一个受限组件，对于受限的<input>，渲染出来HTML元素始终保持value属性的值，此时用户在渲染出来的组件里输入任何值都不起作用
写一个完整的表单元素的实例
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>受限组件和双向绑定</title><script src="../js/react.development.js "></script><script src="../js/react-dom.development.js"></script><!-- 用于解析babel --><script src="../js/babel.min.js"></script>
</head><body><div id="hello"></div><div id="hello2"></div><script type="text/babel">//受限组件,他的class Hello extends React.Component{render(){return <div><input type="text" value='123'/><hr/></div>}}ReactDOM.render(<Hello />,document.getElementById('hello'))//双向数据绑定class Hello2 extends React.Component{state = {value:'12345'}//valueChange = (e)=>{this.setState({value:e.target.value})}render(){return <div><input type="text" value={this.state.value} onChange={this.valueChange}/><p>{this.state.value}</p></div>}}ReactDOM.render(<Hello2 />,document.getElementById('hello2'))</script><!-- radio、checkbox、textarea、select --><hr/><div id="root1"></div><script type="text/babel">//表单元素的双向绑定class Rtx extends React.Component{state = {//单选按钮radioValue:'',//check选中的checkArr:[],//文本域的valuetextareaValue:'',selectArr: ['北京','上海','湖北','广东'],//select选中的地址address:''}//radioChange = (e)=>{this.setState({radioValue:e.target.value})}checkboxChange =(e)=>{//由于组件继承的是purecomponent,因此要将数组复制一次let _checkArr = [...this.state.checkArr]if (e.target.checked) {//将所有选中的复选框的value值，push到一个数组（checkArr）中_checkArr.push(e.target.value)} else {//若取消选中，则将其从checkArr中减掉_checkArr.splice(this.state.checkArr.indexOf(e.target.value), 1)}//利用setState更新checkArrthis.setState({checkArr:_checkArr})}textareaChange=(e)=>{this.setState({textareaValue:e.target.value})}selectChange=(e)=>{this.setState({address:e.target.value})}submit =()=>{console.log(this.state);}render(){let checkInfo=["c1",'c2']let {radioValue,checkArr,textareaValue,selectArr,address } =this.statelet {checkboxChange} =thisreturn <div><div>性别：男<input type="radio" value='man' checked={radioValue=='man'?true:false} onChange={this.radioChange}/>女<input type="radio" value='woman' checked={radioValue=='woman'?true:false} onChange={this.radioChange}/></div><div>{checkInfo.map(function(item,index){return <span>{item}<input type="checkbox" name='box' value={item} key={index} onChange={checkboxChange} checked={checkArr.indexOf(item)!==-1}></input></span> })}</div><div><textarea name="" id="" value={textareaValue} cols="30" rows="10" onChange={this.textareaChange}></textarea></div><div>地址:<select value={address} name="address" onChange={this.selectChange}>{selectArr.map(function(item,index){return <option key={index}>{item}</option>})}</select> </div><button disabled={!radioValue || !address || !checkArr || !textareaValue } onClick={()=>this.submit()}>提交</button></div>}}ReactDOM.render(<Rtx />,document.getElementById('root1'))</script><!-- radio、
</body></html>2.不受限组件
不受限组件： 没有设置value（或者设为null）的input组件是一个不受限组件。杜宇不受限的input组件，渲染出来的元素直接反映用户输入
使用defaultValue属性不使用value可以实现不受限组件的双向数据
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>非受限组件</title><script src="../js/react.development.js "></script><script src="../js/react-dom.development.js"></script><!-- 用于解析babel --><script src="../js/babel.min.js"></script>
</head><body><div id="root1"></div><script type="text/babel">//非受限组件class Rtx extends React.Component {state = {value: '123'}valueChange = (e) => {this.setState({ value: e.target.value })console.log(this.state.value);}render() {return <div><div><input type="text" /><input type="text" defaultValue={this.state.value} onChange={this.valueChange} /><p>{this.state.value}</p></div><div>性别：男<input type="radio" name='sex' value='man' />女<input type="radio" name='sex' value='woman' /></div></div>}}ReactDOM.render(<Rtx />, document.getElementById('root1'))</script><!-- radio、checkbox、textarea、select --><div id="root1"></div><script type="text/babel">//表单元素的双向绑定class Rtx extends React.Component {state = {//单选按钮radioValue: '',//check选中的checkArr: [],//文本域的valuetextareaValue: '',selectArr: ['北京', '上海', '湖北', '广东'],//select选中的地址address: ''}//radioChange = (e) => {this.setState({ radioValue: e.target.value })}checkboxChange = (e) => {//由于组件继承的是purecomponent,因此要将数组复制一次let _checkArr = [...this.state.checkArr]if (e.target.checked) {//将所有选中的复选框的value值，push到一个数组（checkArr）中_checkArr.push(e.target.value)} else {//若取消选中，则将其从checkArr中减掉_checkArr.splice(this.state.checkArr.indexOf(e.target.value), 1)}//利用setState更新checkArrthis.setState({checkArr: _checkArr})}textareaChange = (e) => {this.setState({ textareaValue: e.target.value })}selectChange = (e) => {this.setState({ address: e.target.value })}submit = () => {console.log(this.state);}render() {let checkInfo = ["c1", 'c2']let { radioValue, checkArr, textareaValue, selectArr, address } = this.statelet { checkboxChange } = thisreturn <div><div>性别：男<input type="radio" defaultValue='man' checked={radioValue == 'man' ? true : false} onChange={this.radioChange} />女<input type="radio" defaultValue='woman' checked={radioValue == 'woman' ? true : false} onChange={this.radioChange} /></div><div>{checkInfo.map(function (item, index) {return <span>{item}<input type="checkbox" name='box' defaultValue={item} key={index}onChange={checkboxChange}checked={checkArr.indexOf(item) !== -1}></input></span>})}</div><div><textarea name="" id="" value={textareaValue} cols="30" rows="10" onChange={this.textareaChange}></textarea></div><div>地址:<select defaultValue={address} name="address" onChange={this.selectChange}>{selectArr.map(function (item, index) {return <option key={index}>{item}</option>})}</select></div><button disabled={!radioValue || !address || !checkArr || !textareaValue} onClick={() => this.submit()}>提交</button></div>}}ReactDOM.render(<Rtx />, document.getElementById('root1'))</script>
</body></html>三、常用表单数据绑定
对相同逻辑的表单change事件进行封装
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>表单提交</title><script src="../js/react.development.js "></script><script src="../js/react-dom.development.js"></script><!-- 用于解析babel --><script src="../js/babel.min.js"></script>
</head><body><div id="root1"></div><script type="text/babel">//非受限组件class Rtx extends React.Component {state = {name: 'fxt',sex:'1',address:'上海',textareaValue:'hello world'}//我们发现下面获得改变值的方法都是一样的，所以对一样的逻辑函数进行封装handleChange=(e)=>{console.log(e.target.name);let key = e.target.namethis.setState({[key]:e.target.value})// this.setState({[e.target.name]:e.target.value})}// getName=(e)=>{// this.setState({name:e.target.value})// }// getSex=(e)=>{// this.setState({sex:e.target.value})// }getAddress=(e)=>{this.setState({address:e.target.value})}getTextareaValue=(e)=>{this.setState({textareaValue:e.target.value})}submit = (e) => {// e.preventDefault();alert(JSON.stringify(this.state))}render() {let selectArr=['北京', '上海', '湖北', '广东']let {name,sex,address,textareaValue}=this.statereturn <div><form action=""><label for="">姓名：<input type="text" name='name' defaultValue={name} onChange={this.handleChange}/></label> <label for=""><div>性别：<input type="radio" name="sex" value='1' defaultChecked={sex==1? true:false} id="" onChange={this.handleChange}/>男<input type="radio" name="sex" value='2' defaultChecked={sex==2? true:false} id="" onChange={this.handleChange}/>女</div></label> <label for=""><div>地址:<select defaultValue={address} name="address" onChange={this.getAddress}>{selectArr.map( (item, index) =>{return <option key={index}>{item}</option>})}</select></div></label><label for=""><div>备注：<textarea name="" id="" defaultValue={textareaValue} cols="30" rows="10" onChange={this.getTextareaValue}></textarea> </div></label><button disabled={!name || !address || !textareaValue || !sex} onClick={()=>{this.submit()} }>提交</button></form></div>}}ReactDOM.render(<Rtx />, document.getElementById('root1'))</script>
</body></html>四、注册功能实现
<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>注册表单验证</title><script src="../js/react.development.js "></script><script src="../js/react-dom.development.js"></script><!-- 用于解析babel --><script src="../js/babel.min.js"></script><style>.error{color: red;}</style>
</head><body><div id="root1"></div><script type="text/babel">//非受限组件class Rtx extends React.Component {state = {name: '',nameError:"",passworld:'',passworldError:'',sex:'1',phone:'',phoneError:'',city:'北京',textareaValue:'hello world'}//单独写校验规则的nameChange=(e)=>{let rule= /^[\w-]{4,10}$/ let value=e.target.valuelet error=''if(!value){error='请输入昵称'}else if(!rule.test(value)){error='请输入4-10位的昵称'}else{error=''}this.setState({name:value,nameError:error})}//进行校验的表单元素统一封装handleTest=(e)=>{let ruleArr={passworld:{rule:new RegExp(/^\S*(?=\S{6,12})(?=\S*\d)(?=\S*[A-Z])(?=\S*[a-z])(?=\S*[!@#$%^&*? ])\S*$/),text:'密码',error:'6-12位，至少包括一个大小写字母、数字、特殊字符'},phone:{rule:new RegExp(/^(?:(?:\+|00)86)?1[3-9]\d{9}$/),text:'手机号',error:'请输入正确的手机号'}}let value=e.target.valuelet key = e.target.namelet ruleInfo={}let error=''Object.keys(ruleArr).map((el)=>{if(el==key){ruleInfo=ruleArr[key]}})if(!value){error='请输入'+ruleInfo.text}else if(!ruleInfo.rule.test(value)){error=ruleInfo.error}else{error=''}this.setState({[key]:value,[key+'Error']:error})}//不进行校验的表单通过自定义属性实现获得要设置的值的key键handleChange=(e)=>{console.log(e.target.name);let key = e.target.namethis.setState({[key]:e.target.value})// this.setState({[e.target.name]:e.target.value})}//提交想提交值submit = (e) => {e.preventDefault()//阻止默事件let {name,passworld,sex,phone,city,textareaValue} =this.statelet data={name,passworld,sex,phone,city,textareaValue}alert(JSON.stringify(data))}render() {let selectArr=[{id:1,text:'北京'},{id:2,text: '上海'}, {id:3,text:'湖北'}]let {name,nameError,passworld,passworldError,sex,phone,phoneError,city,textareaValue}=this.statereturn <div><form action=""><label for="">昵称：<input type="text" name='name' defaultValue={name} onChange={this.nameChange}/><span className='error'> * {nameError}</span></label> <label for=""><div>密码：<input type="text" name='passworld' defaultValue={passworld} onChange={this.handleTest}/><span className='error'> * {passworldError}</span></div></label> <label for=""><div>性别：<input type="radio" name="sex" value='1' defaultChecked={sex==1? true:false} id="" onChange={this.handleChange}/>男<input type="radio" name="sex" value='2' defaultChecked={sex==2? true:false} id="" onChange={this.handleChange}/>女</div></label> <label for="">手机号：<input type="text" name='phone' defaultValue={phone} onChange={this.handleTest}/><span className='error'> * {phoneError}</span> </label> <label for=""><div>城市:<select defaultValue={city} name="city" onChange={this.handleChange}>{selectArr.map( (item, index) =>{return <option value={item.id} key={index}>{item.text}</option>})}</select></div></label><label for=""><div>备注：<textarea name="textareaValue" id="" defaultValue={textareaValue} cols="30" rows="10" onChange={this.handleChange}></textarea> </div></label><button disabled={!name || nameError|| !passworld || passworldError|| !sex || !phone ||phoneError || !city ||!textareaValue } onClick={this.submit }>提交</button></form></div>}}ReactDOM.render(<Rtx />, document.getElementById('root1'))</script>
</body></html>