使用javascript时出现代码错误

我的用户名和密码验证代码出现了一个错误，我不知道如何修复它 我正在尝试使用

function checkForm(form) {
    if (form.username.value == "") {
        alert("Error: Username cannot be blank!");
        form.username.focus();
        return false;
    }
    re = /^\w+$/;
    if (!re.test(form.username.value)) {
        alert("Error: Username must contain only letters, numbers and underscores!");
        form.username.focus();
        return false.pwd2.value) {
        if (form.pwd1.value.length < 8) {;
        }

        if (form.pwd1.value != "" && form.pwd1.value == form alert("Error: Password must contain at least eight characters!"); form.pwd1.focus();
            return false;
        }
        if (form.pwd1.value == form.username.value) {
            alert("Error: Password must be different from Username!");
            form.pwd1.focus();
            return false;
        }
        re = /[0-9]/;
        if (!re.test(form.pwd1.value)) {
            alert("Error: password must contain at least one number (0-9)!");
            form.pwd1.focus();
            return false;
        }
        re = /[a-z]/;
        if (!re.test(form.pwd1.value)) {
            alert("Error: password must contain at least one lowercase letter (a-z)!");
            form.pwd1.focus();
            return false;
        }
        re = /[A-Z]/;
        if (!re.test(form.pwd1.value)) {
            alert("Error: password must contain at least one uppercase letter (A-Z)!");
            form.pwd1.focus();
            return false;
        }
    } else {
        alert("Error: Please check that you've entered and confirmed your password!");
        form.pwd1.focus();
        return false;
    }

    alert("You entered a valid password: " + form.pwd1.value);
    return true;
}

我正在尝试将此代码用于此html

 <form name="hw4Form" action="" autocomplete="off">
<br>
<fieldset name="LoginInfo">
<input id="username" type="text" name="username" placeholder="username" size="30">
<br>
<br>
Password:
<br>
<input id="pwd1" type="password" name="pwd1" placeholder="password" required="required" size="30">
<span id="pwd1Hint" class="hint">Password is too short (must be at least 8 characters)</span>
<br>
Repeat Password:
<br>
<input id="pwd2" type="password" name="pwd2" placeholder="password" required="required" size="30">
<span id="pwd2Hint" class="hint">Passwords don't match</span>
<br>
<br>

我的代码编辑软件有一个错误，但我不知道如何修复它 我还想确保此javascript适用于html，如下所示：

 if(form.pwd1.value != "" && form.pwd1.value == form

应该是：

 if(form.pwd1.value != "" && form.pwd1.value == form.username.value)) {

或者类似的东西

---

在html中，您还需要使用console.logform或其他字段关闭表单，以检查js执行过程。或者为什么不使用firebug调试该函数呢

错误消息是什么？丢失；在第30列之前的语句中，缺少错误；在第30列之前的语句中，但它没有任何帮助，除非我在使用IE时遗漏了一些东西。改变它，使用chrome或firefox和firebug进行调试。您将看到更多详细信息