React练习 9 :求出数组中所有数字的和

需求：求出数组中所有数字的和

解析：需使用受控组件，并绑定onChange事件（不绑定，React会提醒你。。。)

import React,{useState,useEffect} from 'react';
import ReactDOM from 'react-dom';
import './index.css';


function Sum(){
    const [val,setVal]=useState("1,2,3,4,5,6,7,8,9,10,11,12,13,14,15");
    const [sum,setSum]=useState('');
    const handleVal = function(e) {
        //let newVal=e.target.value;
        //newVal=newVal.replace(/[^(\d)|(,)]/,'');
        setVal(e.target.value.replace(/[^(\d)|(,)]/,''));
        //console.log(val);
    };
    const handleClick =function(){
        var sum=0;
        var inputs=val.split(',');
        for(var i in inputs){
            sum += parseInt(inputs[i]);
        }
        setSum(sum);
    }
    return(
        

            
                <input 
                type="text" 
                value={val}
                onChange={handleVal}
                />
                输入数字求和，数字之间用半角","号分隔
            
            
求和
            {sum}
        
    );
}

ReactDOM.render(
    ,
    document.getElementById('root')
)