判断checkbox是否选中
在一个form中，同时有checkbox和submit提交按钮。现在想达到的效果是，当checkbox选中时，submit按钮才能提交；否则提示返回。请问如何做到？最好有代码示例，谢谢！
[解决办法]
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title></title></head><script>window.onload = function(){ document.getElementById("btn").onclick=function(){ var flag1 = document.getElementById("ckb1").checked; if(!flag1){ alert("请先选择复选框1"); return false; } var flag2 = document.getElementById("ckb2").checked; if(!flag2){ alert("请先选择复选框2"); return false; } alert("提交表单"); return true; }}</script><body><input id="ckb1" type="checkbox"/><input id="ckb2" type="checkbox" checked="checked"/><input id="btn" type="submit" value="submit"/></body></html>
[解决办法]
<input type="checkbox" name="checkbox[]" value="原因A" />原因A<br /><input type="checkbox" name="checkbox[]" value="原因B" />原因B<br /><input type="checkbox" name="checkbox[]" value="原因C" />原因C<br /><input type="checkbox" name="checkbox[]" value="others" />其他<input type="text" id="txt" name="reason" style="display:none;" /><input id="btnEditOK" type="Submit" disabled="true" class="btnbig" value="提交" onmouseover="this.className='btnbig_over'" onMouseOut="this.className='btnbig'" /><script type="text/javascript"> var input=document.getElementsByName("checkbox[]"); var txt = document.getElementById("txt"); var btnEditOK = document.getElementById("btnEditOK"); for(var i=0;i<input.length;i++){ input[i].onclick=function(){ var n=0; for(var l=0;l<input.length;l++){ txt.style.display="none"; if(input[l].checked){ n++; if(input[l].value=="others"){ txt.style.display=""; } } } if(n==0){ btnEditOK.disabled=true; }else{ btnEditOK.disabled=false; } } }</script>
[解决办法]
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title> New Document </title> <meta http-equiv="Content-Type" content="text/html" charset="gbk"/> <meta name="Generator" content="EditPlus"> <meta name="Author" content=""> <meta name="Keywords" content=""> <meta name="Description" content=""> </head><script type="text/javascript"> function check(){ var checkBox=document.getElementsByTagName("input"); var i,num=0; for(i=0;i<checkBox.length-1;i++){ if(!checkBox[i].checked){ num++; } if(num==checkBox.length-1){ alert("请勾选复选框！"); return false; } } return true; }</script> <body> <form action="#" method="post" onsubmit="return check();"> <label>选则你喜欢的数字？</label><br/> <label>1</label><input type="checkbox"/><br/> <label>2</label><input type="checkbox"/><br/> <label>3</label><input type="checkbox"/><br/> <label>4</label><input type="checkbox"/><br/> <label>5</label><input type="checkbox"/><br/> <input type="submit" value="提交"/> </form> </body></html>