Два вопроса здесь:
Если вы не хотите отправлять свою форму (например, введенные данные неверны), вам нужно будет запретить ее отправку. В JavaScript вы можете сделать это с помощью preventDefault().
Итак, для этого я добавил строку event.preventDefault() к вашему if statement, которая проверяет наличие ошибок. Помните, что вам нужно передать параметр event в вашу функцию, чтобы заставить preventDefault() работать.
Во-вторых, вам нужно проверить, если value вашего поля электронной почты includes что-то.
У вас есть поле электронной почты, например: var email = document.getElementById('email');, поэтому вам нужно проверить value следующим образом: email.value.includes('bla').
Все вместе, ваш скрипт прекрасно работает:
function validate_form(event) {
var forename = document.getElementById("forename");
var surname = document.getElementById("surname");
var username = document.getElementById("username");
var password = document.getElementById("password");
var re_password = document.getElementById("re_password");
var email = document.getElementById("email");
var errors = 0
var special_chars = "<>@!#$%^&*()_+[]{}?:;|'\"\\,./~`-=";
if (forename.value == "") {
//document.getElementById("forename").style.background = "red";
forename_confirmation.style.visibility = 'visible';
var errors = errors + 1
} else
for (var i = 0; i < forename.value.length; i++) {
if (special_chars.indexOf(forename.value.charAt(i)) != -1) {
forename_chars.style.visibility = 'visible'
}
}
if (surname.value == "") {
//document.getElementById("surname").style.background = "red";
surname_confirmation.style.visibility = 'visible';
var errors = errors + 1
} else
for (var i = 0; i < surname.value.length; i++) {
if (special_chars.indexOf(surname.value.charAt(i)) != -1) {
surname_chars.style.visibility = 'visible'
}
}
if (username.value == "") {
//document.getElementById("username").style.background = "red";
username_confirmation.style.visibility = 'visible';
var errors = errors + 1
} else
for (var i = 0; i < username.value.length; i++) {
if (special_chars.indexOf(username.value.charAt(i)) != -1) {
username_chars.style.visibility = 'visible'
}
}
if (password.value == "") {
//document.getElementById("password").style.background = "red";
pass_confirmation.style.visibility = 'visible';
var errors = errors + 1
}
if (password.value != re_password.value) {
//document.getElementById("re_password").style.background = "red";
repass_confirmation.style.visibility = 'visible';
var errors = errors + 1
}
if (email.value == "") {
//document.getElementById("email").style.background = "red";
var errors = errors + 1
}
if (errors != "0") {
alert("Whoops! Looks like you didn't enter your details properly");
event.preventDefault(); // Prevent the form from submitting
}
if (!email.value.includes("@") || !email.value.includes(".")) {
//document.getElementById("email").style.background = "blue";
email_confirmation.style.visibility = 'visible';
return false;
}
return (true);
}
<!DOCTYPE html>
<html>
<head>
<title>Login form</title>
<link rel="stylesheet" type="text/css" href="Login Form CSS.css">
<script src="Registration function.js" defer></script>
<body>
<div class="loginbox">
<img src="Logo.jpg" class="avatar">
<h1> Create Account </h1>
<form name="login-form">
<div id="forename_confirmation"> Please fill in this box </div>
<div id="forename_chars"> Don't use special characters</div>
<p>Forename
<p>
<input type="text" name="forename" id="forename" placeholder="Enter Forename here">
<div id="surname_confirmation"> Please fill in this box </div>
<div id="surname_chars"> Don't use special characters</div>
<p>Surname
<p>
<input type="text" name="surname" id="surname" placeholder="Enter Surname here">
<div id="username_confirmation"> Please fill in this box </div>
<div id="username_chars"> Don't use special characters</div>
<p>Username
<p>
<input type="text" name="username" id="username" placeholder="Enter Username here">
<div id="pass_confirmation"> Please fill in this box </div>
<div id="pass_chars">Don't use special characters</div>
<p>Password
<p>
<input type="password" name="password" id="password" placeholder="Enter Password here">
<div id="repass_confirmation"> Passwords do not match </div>
<p>Re-enter Password
<p>
<input type="password" name="re_password" id="re_password" placeholder="Re-enter your password here">
<div id="email_confirmation"> Please enter a valid email </div>
<p>Email
<p>
<input type="email" name="email" id="email" placeholder="Enter Email here">
<!--
<p>Gender<p>
<input type="radio" id="Male" name="Gender" value="Male">Male</input>
<input type="radio" id="Female" name="Gender" value="Female">Female</input>
-->
<button onclick="validate_form(event)" type="Submit" value="True" name="button-submit"> Submit </button>
<br />
<br />
<a href="#"> Forgot your password? </a>
<br />
<a href="#"> Already got an account? </a>
<br /><br />
</form>
<!-- <button onclick="validate_form()" type="submit"> Validate </button> -->
</div>
</body>
</head>
<script>
forename_confirmation.style.visibility = 'hidden'
forename_chars.style.visibility = 'hidden'
surname_confirmation.style.visibility = 'hidden'
surname_chars.style.visibility = 'hidden'
username_confirmation.style.visibility = 'hidden'
username_chars.style.visibility = 'hidden'
pass_confirmation.style.visibility = 'hidden'
pass_chars.style.visibility = 'hidden'
repass_confirmation.style.visibility = 'hidden'
email_confirmation.style.visibility = 'hidden'
</script>
</body>
</html>