How to use JavaScript loop practice to find the palindrome number between 1~9999-JS Tutorial-php.cn

How to use JavaScript loop practice to find the palindrome number between 1~9999

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Release： 2017-10-13 09:18:05

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Find an integer between 1 and 9999, determine whether it is a palindrome number, if so, output and output the number of digits in this number

<script type="text/javascript">/*先整理思路、、、、、    
var n = 3223;   只要前后颠倒相等就是回文数
整数的位数： n.length
for(var i = n.length - 1; i <= o ; i--){
    m.push(n[i]);
}
    document.write(m);    
    */
    function huiwen(){    var num = prompt("请输入一个整数");
    document.write("你输入的数是：" + num + "<br>");    
    var n ="";  //定义颠倒后的字符串 
    if(num<1){
       document.write("不要输入负数");
       }else if (num >= 1 &&num <10){
            document.write("这是一个回文数" + "<br>");
            document.write("这个回文数的位数是：1");
       }        else{          for(var i = num.length ; i >= 0  ; i--){ 
              var num1 = num.charAt(i);     //charAt等同于数组的下标，这样通过for循环就可以把输入的整数顺序颠倒
              n = n.concat(num1);            // 但是num1并不是一个整数，也不是一个字符串，没法跟num比较，用concat（）将它们连接成一个字符串            }
             document.write( n + "：");      //得到的回文数输出一下             
             if( n == num){
               document.write("这是一个回文数" + "<br>");
               document.write("这个回文数的位数是：" + n.length)
            }else{
               document.write(&#39;这不是一个回文数&#39;);
            }
       }
}</script>
</head>

<body>
<input type="button" value="开始" onClick="huiwen()">
</body>

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