本来这个小玩意很简单，不用记录到博客里，但今天是娱乐日，要快落一天，为了减轻负罪感，假装自己又学了点新东西
<!DOCTYPE html><html><head> ???<meta charset="utf-8"> ???<meta http-equiv="X-UA-Compatible" content="IE=edge"> ???<title>Page Title</title> ???<meta name="viewport" content="width=device-width, initial-scale=1"> ???<link rel="stylesheet" type="text/css" media="screen" href="main.css"> ???<script src="jquery-3.3.1.min.js"></script></head><body> ???<input type="text" placeholder="请输入地址"><!--placeholder并不能在输入框获得聚焦后自动消失--> ???<br> ???<input type="text" id="address" value="请输入邮箱地址"> ???<br> ???<input type="text" id="password" value="请输入密码" ss="qq"> ???<script> ???????var test = document.getElementById("password"); ???????console.log(test.getAttribute("ss"));//可以获取自定义特性欸 ???????$("#address").focus(function(){ ???????????var text_value = $(this).val(); ???????????if(text_value == "请输入邮箱地址"){ ???????????????$(this).val(""); ???????????} ???????}); ???????$("#address").blur(function(){ ???????????var text_value = $(this).val(); ???????????if(text_value == ""){ ???????????????text_val("请输入邮箱地址"); ???????????} ???????}); ???????//密码框同理 ???</script></body></html>JQuery：聚焦清空输入框值，失焦恢复默认值
原文地址：https://www.cnblogs.com/linbudu/p/10540565.html