<!DOCTYPE html> <html lang="en" xmlns="http://www.w3.org/1999/html" xmlns="http://www.w3.org/1999/html"> <head> <meta charset="gb2312"> <title>test</title> <script src="jquery-1.11.3.js"></script> <script> $(document).ready(function(){ $("form").submit(function(e){ var username=$("#username").val(); if(!username){ alert("請輸入用戶名"); }else{ alert($("#username").val()); } }) }) </script> </head> <body> <form method="post" id="login-form"> <p><label for="username">用戶名:</label><input type="text" name="username" id="username" ></p> <p><label for="password">密碼:</label><input type="password" name="password" id="password"></p> <p><input type="submit" id="submit-btn"></p> </form> </body> </html>
submit 事件會在表單中的確認按鈕被點擊時發生,但不像click等事件同樣是綁定當前觸發該事件的元素,submit綁定的應該是整個form表單。html
function sub(){ var username=document.getElementById("username"); var user=username.value; if(!user){ alert("請輸入用戶名"); }else{ alert(user); } } var form=document.getElementById("login-form"); form.addEventListener("onsubmit",sub,false);
這是原生js的。jquery