console
let nameInput = document.querySelector('#name');
let emailInput = document.querySelector('#email');
let emailTip = document.querySelector('#emailTip');
function check(){
let name = nameInput.value;
let email = emailInput.value;
let pattern = /^\S+@\S+\.\S+$/;
if (name.length <2 ||
!email.includes('@') ||
!email.includes('.') ||
!pattern.test(email)){
emailTip.classList.remove('hidden');
emailInput.style.border = '2px solid red';
}else{
emailTip.classList.add('hidden');
}
}
nameInput.oninput = check;
emailInput.oninput = check;
<input id="name" placeholder="请输入姓名">
<input id="email" placeholder="请输入邮箱">
<p id= 'emailTip' class="hidden">输入内容错误</p>
.hidden {
display: none;
}