JavaScript 实现表单非空验证与提交阻断

 <!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
div {
    width: 600px;
    height: 600px;
    margin: 50px auto;
    background-color: skyblue;
    padding: 20px;
}

div input {
    width: 520px;
    height: 50px;
    margin-top: 50px;

}
    </style>
</head>

<body>
<div>
<form action="">
    <input type="text" name="name" placeholder="输入用户名"><br>
    <p class="nameTip"></p>
    <input type="password" name="password" placeholder="输入密码"><br>
    <p class="passwordTip"></p>
    <input type="submit" name="submit" value="按钮">
</form>
</div>
    <script>
var formEle = document.querySelector('form')
var nameinput = document.querySelector('input[name="name"]')
var passwordinput = document.querySelector('input[name="password"]')
var pnameTip = document.querySelector('.nameTip')
var ppasswordTip = document.querySelector('.passwordTip')
//是否为空判定
function checkUserNameNull(){
    if(nameinput.value==''){
            pnameTip.innerHTML='输入名字'
            return false
        }else{
            pnameTip.innerHTML=''
            return true
        }
}
//失去焦点进行用户名是否为空验证
    nameinput.οnblur=function (){
        checkUserNameNull()
    }
//是否为空判定
function checkPasswordNull(){
    if(passwordinput.value==''){
            ppasswordTip.innerHTML='输入名字'
            return false
        }else{
            ppasswordTip.innerHTML=''
            return true
        }
}
//失去焦点进行密码框是否为空验证
    passwordinput.οnblur=function (){
        checkPasswordNull()
    }

//提交时验证
formEle.onsubmit = function (e) {
    e.preventDefault()
    //阻止表单默认提交
    var nameisok=checkUserNameNull()
    var passwordisok= checkPasswordNull()
//都满足不为空提交 
    if(nameisok && passwordisok){
        location.href = 'https://www.baidu.com/'
    }
}
//键值提交
document.οnkeyup=function (e){
    var keyCode=e.keyCode|| e.which
    if(keyCode==13&&e.shiftKey){
        var nameisok=checkUserNameNull()
        var passwordisok= checkPasswordNull()
        if(nameisok && passwordisok){
        location.href = 'https://www.baidu.com/'
    }
    }
}
    </script>
</body>

</html>