js表单验证 页面跳转

function checkSend()
{
if (document.all.toinput.value=="") {
alert("不能为空") ;
document.all.toinput.focus();
return false;
}
if (document.all.subjectinput.value=="") {
if (confirm("是否要为空?")) {
document.all.sendform.action="2.html";
}else{
document.all.subjectinput.focus();
return false;
}
}
document.all.sendform.action="2.html";
return true
}

function checkSend(oform)
{
if(document.all.toinput.value == ""){
alert("不能为空");
document.all.toinput.focus();
return;
}else if(document.all.subjectinput.value == ""){
if(confirm("是否要为空")){
window.open("2.html");
}else{
document.all.subjectinput.focus();
return;
}
}else{
window.open("2.html");
}

}