javascript - 使用 Javascript 进行电子邮件验证，给出带有有效电子邮件地址的错误消息

Question

我正在尝试仅使用 Javascript 验证电子邮件地址字段，并且我已经测试了许多用于验证的表达式，但每次即使在输入有效的电子邮件格式后，我也会收到错误消息。我也在记录输入的值，它每次都给出“假”而不是我输入的电子邮件地址。请问我该如何解决？提前致谢。这是代码：

function database(){
                let name = document.querySelector('#name').value;
                let email = document.querySelector('#email').value;
                let cell = document.querySelector('#cell').value;

                let validation = () => {
                    function validateEmail(sEmail){
                        let filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
                        if (filter.test(sEmail) == false){   
                            alert('Please provide a valid email address');
                            console.log(sEmail); 
                            return false;
                        } else{
                            return true;
                            console.log(sEmail);
                        }
                    }

                    if ( name == '' || name == null  ){
                        alert('Please Fill Name');   
                    } else if ( email == '' || email == null  ){
                        alert('Please Fill Email');
                    } else if ( !(email = '' || email == null) ){
                        validateEmail(email);
                    } else if ( cell == '' || cell == null || isNaN(cell) ){
                        alert('Please Fill Cell');
                    } else {
                        console.log('Function is Running Ok')
                    }
                }
                validation();
            }
            let button = document.querySelector('#button');
            button.addEventListener('click', database);

<div class="form" id="form">
			<h2 class="formtitle">Put the input data</h2>
			<form action="" method="post" id="databaseinput">
				<input type="text" name="name" id="name" placeholder="Name" required />
				<input type="email" name="email" id="email" placeholder="Email" required />
				<input type="number" name="cell" id="cell" placeholder="Cell Number" required />
				<input type="button" name="submit" id="button" value="Submit" />
			</form>
        </div>

标签： javascriptformsvalidation