<body> <form> 请选择你爱好:<br> <input type="checkbox" name="hobby" id="hobby1"> 音乐 <input type="checkbox" name="hobby" id="hobby2"> 登山 <input type="checkbox" name="hobby" id="hobby3"> 游泳 <input type="checkbox" name="hobby" id="hobby4"> 阅读 <input type="checkbox" name="hobby" id="hobby5"> 打球 <input type="checkbox" name="hobby" id="hobby6"> 跑步 <br> <input type="button" value = "全选" onclick = "checkall();"> <input type="button" value = "全不选" onclick = "clearall();"> <p>请输入您要选择爱好的序号，序号为1-6:</p> <input id="wb" name="wb" type="text" > <input name="ok" type="button" value="确定" onclick = "checkone();"> </form> <script type="text/javascript"> function checkall(){ //全选 var hobby = document.getElementsByTagName("input"); for(var i=0;i<hobby.length;i++){ if(hobby[i].type=="checkbox"){ hobby[i].checked=true; } } } function clearall(){ // 全不选 var hobby = document.getElementsByName("hobby"); for(var i=0;i<hobby.length;i++){ if(hobby[i].checked==true){ hobby[i].checked=false; } } } function checkone(){ //选一个 var num=0; var j=document.getElementById("wb").value; var hobby=document.getElementsByName("hobby"); if(j<=0||j>6){ alert("请输入正确的数字！"); }else { hobby[j-1].checked=true; } for(var i=0;i<hobby.length;i++){ if(hobby[i].checked==true){ autoCheck("hobby",3); } } } // 限制单个选中的最大个数 function autoCheck(name,limit){ var hobby=document.getElementsByName(name); function check() { var num=0; for(var i=0;i<hobby.length;i++) { if(hobby[i].checked){num++} if(num>limit) { return false; } } return true; } function checkedNum(){ for(var i=0;i<hobby.length;i++){ if(!check()){ alert("只能选择"+limit+"项哦!"); hobby[i].checked=false; } } } } </script> </body>
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