javascript限制复选框最多选中几项

来源：互联网发布：淘宝运费模板删除不了编辑：程序博客网时间：2024/06/05 08:47
<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>限制复选框最多选几项</title></head><body><p>    最多选中<select id="choosenum" onchange="change(this)">        <option value="a" selected>1</option>        <option value="b">2</option>        <option value="c">3</option>        <option value="d">4</option>        <option value="e">5</option>        <option value="f">6</option>    </select>项</p><p>    <input type="checkbox" name="checkmost">    <input type="checkbox" name="checkmost">    <input type="checkbox" name="checkmost">    <input type="checkbox" name="checkmost">    <input type="checkbox" name="checkmost">    <input type="checkbox" name="checkmost"></p><script>    var  maxnum=1,num= 0,checkboxs=document.getElementsByName("checkmost"),         alength=checkboxs.length,choosenum=document.getElementById("choosenum");   window.onload=function(){       for(var i=0;i<alength;i++){           checkboxs[i].onclick=function(){               if(this.checked){                   if(num==maxnum||num>maxnum){                       return false;                   }                   num++;               }               else {                   num--;               }           }       }   }   function change(that){       var selectindex=that.selectedIndex;//获得是第几个被选中了       var selectText =that.options[selectindex].text; //获取options中间的文本值       for(var i=0;i<alength;i++){           checkboxs[i].checked=false;       }       maxnum=selectText;       num=0;   }</script></body></html>
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