JSFiddle - React, Tailwind, and code Playground

HTML

<p>This is a test for <a href="http://stackoverflow.com/questions/3931621/multiple-login-users-javascript">Stackoverflow</a></p>
<form name="login" action="" method="post">
    Login: <input type="text" name="loginid" id="loginid" /> <br/>
    Password: <input type="text" name="pword" id="pword" /><br/><br/>
    <input type="button" value="Submit" onClick="validate(this.form)" />

JavaScript

function validate(loginForm) {
    var booValid = true;
    var strErrorMessage = "";
    var minLength = 5;
    var maxLength = 10;

    if (loginForm.pword.value.length < minLength) {
        strErrorMessage = "password must at least 5 characters\n";
        booValid = false;
    }
    else if (loginForm.pword.value.length > maxLength) {
        strErrorMessage = "pasword must not more than 10 characters\n";
        booValid = false;
    }
    if (loginForm.loginid.value != "jss1@yahoo.com.au" && loginForm.loginid.value != "jss1@yahoo.com.au" && loginForm.loginid.value != "jss1@yahoo.com.au") {
        strErrorMessage += "Incorrect Login ID, Please try again\n";
        booValid = false;
    }
    if (!booValid) {
        alert(strErrorMessage);
    }
}