请老师检查代码

来源：4-10 编程练习

xcn_aaaa

2022-07-11 15:55:32

<!DOCTYPE html>
<html>
    <head lang="en">
        <meta charset="UTF-8">
        <title>输入文本</title>
    </head>
    <body>
        <p>字数限制在30字内，<span>您还可以输入<b>30</b> 字</span></p>
        <textarea cols="50"  rows="7"  id="text"></textarea>
        <script type="text/javascript">
            //补充代码
            var oTextarea = document.querySelector('textarea');
            var oSpan = document.querySelector('span');
            // 绑定监听事件
            oTextarea.oninput = function(){
                var len = oTextarea.value.length;
                var wlen = 30-len;
                if(wlen>=0){
                    oSpan.innerHTML = "您还可以输入<b>"+Math.abs(wlen)+"</b>字";
                }else{
                    oSpan.innerHTML = "您已经超出<b>"+Math.abs(wlen)+"</b>字";
                }

            }
        </script>
    </body>
</html>

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