表单提交前验证

function checkForm(frm){ 
var flag = true; 
var exp1 = document.getElementById(frm).getElementsByTagName("input")[0].value.replace(/(^\s*)|(\s*$)/g,""); 
var exp2 = document.getElementById(frm).getElementsByTagName("input")[1].value.replace(/(^\s*)|(\s*$)/g,""); 
if(exp1==""||exp1.length==0){ 
alert("第一项不能为空!"); 
document.getElementById(frm).getElementsByTagName("input")[0].focus(); 
flag = false; 
}else if(exp1.length>10){ 
alert("超出长度!"); 
document.getElementById(frm).getElementsByTagName("input")[0].focus(); 
flag = false; 
}else if(exp2==""||exp2.length==0){ 
alert("第二项不能为空!"); 
document.getElementById(frm).getElementsByTagName("input")[1].focus(); 
flag = false; 
}else if(exp2.length>10){ 
alert("超出长度!"); 
document.getElementById(frm).getElementsByTagName("input")[1].focus(); 
flag = false; 
}else{ 
flag = true; 
} 
return flag; 
} 
function subForm(){ 
if(checkForm(frm)){ 
document.getElementById(frm).submit(); 
} 
return false; 
}