简单javascript问题 在线等
我想用Javascript判断用户名输入是否为空。
为什么用记事本保存为html文件打开时，会出现网页错误的现象。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN ">
<html>
<head>
<meta http-equiv= "Content-Type " content= "text/html; charset=UTF-8 ">
<title> Insert title here </title>
<script type= "text/javascript " language= "javascript ">
function userCheck(){
var f=document.form1;
var username=f.username.value;
if(username= " "){
window.alert( "用户名不能为空！ ")
f.username.focus();
return false;
}
else
{
//send_request( 'check.jsp?username '=+username);
}
}
}
</script>
</head>
<body> <form method= "post " name= "form1 ">
<p> 用户名：
<input type= "text " name= "username ">
<input type= "button " value= "唯一性检查 " name= "check " onclick= "userCheck() ">
<input type= "button " value= "提交 " name= "submit ">
</p> <p> </p> <p> </p> <p> </p> <p> </p> </form>
</body>
</html>
[解决办法]
晕，你滴大括号不匹配！！！
删除第 20 滴大括号！！！
<script type= "text/javascript " language= "javascript ">
function userCheck(){
var f=document.form1;
var username=f.username.value;
if(username= " "){
window.alert( "用户名不能为空！ ")
f.username.focus();
return false;
}
else
{
//send_request( 'check.jsp?username '=+username);
}
}
//} 删除它~~~，哈
</script>
[解决办法]
if(username= " "){
js判断相等用==
if(username== " "){