{
var mem_value = form1.amount.value
for(var i=0i<mem_value.lengthi++)
{
if(mem_value.charAt(i)<'0' || mem_value.charAt(i)>'9')
{
alert("产品数量只能为数字！")
document.form1.amount.focus()
return false
}
}
}if(document.form1.price.value.length>1)
{
var mem = form1.price.value
for(var i=0i<mem.lengthi++)
{
if(mem.charAt(i)<'0' || mem.charAt(i)>'9')
{
alert("单价只能为数字！")
document.form1.price.focus()
return false
}
}
}return true
我来举个例子，很简单的<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
function formCheck(){//表单验证
var userForm=document.forms.userForm
if(userForm.username.value==null||userForm.username.value.length<=0){
alert("用户名不能为空")
return false
}else if(userForm.username.value.length<6||userForm.username.value.length>20){
alert("用户名必须为6-20位")
return false
}else if(userForm.password.value==null||userForm.password.value.length<=0){
alert("密码不能为空")
return false
}else if(userForm.password.value.length<6||userForm.password.value.length>20){
alert("密码必须为6-20位")
return false
}else{
userForm.submit()
}
}
</script>
</head>
<body>
<form action="" name="userForm">
userName:<input type="text" name="username"><br>
password:<input type="password" name="password"><br>
<input type="button" value="提交" onclick=" formCheck()">
</form>
</body>
</html>
