登录不起作用

尊敬的Stackoverpowers，

对于学校，我正在制作一个简单的社交媒体网站，我需要证明你可以登录。我对Javascript没有那么多经验，所以我试图将我在youtube和w3school上找到的知识和信息结合起来，并带来了这个。只有当我按下登录按钮时，它才不会做任何事情（据我所见）。

附言：我知道这个网站真的很难看，但它的一些特定功能正在发挥作用：3

var count= 2;
 
function validate(){
 
    var username = document.login.username.value;
    var password = document.login.password.value;
    var valid= false;
    var usernameArray = ["Gdp", "Hekman", "Koning", "ErikHekman", "ThijsWaardenburg", "Ronald", "RonaldVanEssen" ];
    var passwordArray = ["Gdp123", "Hekman123", "Koning123", "ErikHekman123", "ThijsWaardenburg123", "Ronald123", "RonaldVanEssen123"];
 
    for (var i = 0; i < usernameArray.length; i++)
 
{
 
    if ((username == usernameArray[i]) && (password == passwordArray[i]))
    {
        valid = true;
        break;
    }
}
 
    if (valid)
    {
        alert("Log in was succesfull!")
        window.location = "timeline";
        return false;
    }
    var again = "tries";
    if (count ==1)
    {
        again = "try"
    }  
    if (count >= 1)
    {
        alert("Wrong password or username")
        count--;
    }
    else
    {
        alert("Too many attempts");
        document.login.username.value = "You are now blocked";
        document.login.pass.value = "You are now blocked";
        document.login.username.disabled = true;
        document.login.password.disabled = true;
        return false;
    }
}

html {font-family:Arial, Helvetica, sans-serif; color:#333;}
body { background:#CCC; margin:0; }
#container { width:900px; margin:0 auto; background:#FFF; }
#header { width:100%; height:60px; border-bottom:1px solid #c7c7c7; background:#3f0b04; text-align:center; }
#header h1 {color:#e7c321; }
 
#logo { float:left; width:40px; height:40px; margin:10px; background:#CCC;}
#navbar { height:36px; clear:both; background-color:#e7c321; }
#navbar ul { margin:0; padding:0; list-style-type:none; }
#navbar ul li { padding:10px; float:left; }
#navbar ul li a { font size:12px; float:left; padding:0 0 0 20px; display:block; }
#banner { background:#3f0b04; heigth:120px; clear:both; padding:20px; text-align:center; color:#FFF; margin:10px 0 2px 0;}
#middle-column { float:left; width:858px; height:500px; border:1px solid #333; color:#000; background:#bcbab4; padding:20px; text-align:center; }
#login-logo {width:100%; ; height:200px; float:center;}
#login-form {float:center; width:175px; }
#submit {width:170px; float:center;}
#register {width:170px; float:center;}
 
#footer { padding:20px; clear:both; color:#FFF; background-color:#3f0b04; text-align:center; }

<div id="container">
    <!-- HEADER -->
    <div id="header">
        <div id="logo"><img src="http://imgur.com/578H3e8.png"></img></div>
        <h1>BroCialize</h1>
        <div id="navbar">
            <ul>
                <li><a href="url"></a></li>
                <li><a href="url"></a></li>
                <li><a href="url"></a></li>
            </ul>
        </div>
    </div>
    <!-- CONTENT AREA -->
    <div id="content-area">
        <div id="banner">This site is Legen...wait for it...Dary</div>
        <div id="middle-column">
            <div id="login-logo"><img src="http://imgur.com/uelX4ie.png></img></div>
            <div id="login-form">
                <form method="POST">
                    <input type="text" name="username" placeholder="username" />
                    <br>
                    <input type="password" name="password" placeholder="password" />
                    <br>
                </form>
                <button id="submit">Log in</button>
                <br>
                <button id="register">Register</button>
            </div>
 
        </div>
    </div>
    <!--FOOTER -->
    <div id="footer">Copyright by BroCialize - 2016</div>
</div> <!-- END CONTAINER -->

很抱歉，如果我问新手问题，我只是在寻求一些帮助。提前感谢

-iWnB