本文主要是介绍【知了堂学习笔记】_JavaScript之DOM操作案例（ATM机），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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js操作DOM的小案例——ATM机
<!DOCTYPE html>
<html><head><meta charset="UTF-8"><title></title></head><style type="text/css">div{width: 300px;height:200px;margin: 0 auto;border: 1px solid black;border-radius: 5px;text-align: center;}p{font-size: 20px;}input{width: 150px;height:20px;}button{border: 0px;padding: 5px;background-color: green;color: white;}</style><body><div><p>ATM机</p><p><label>账号：</label><input type="text" id="account"></p><p><label>密码：</label><input type="password" id="passwordatm"></p><p onclick="login()"><button >登录</button></p></div></body>
</html>
<script>var i=2;//输入的次数//判断卡号是否位数字function isNaNAccount(account){return isNaN(account);}//判断输入的卡号和密码是否为空function isNaNAccountAndPwd(account,passwordatm){if((account.length>0)&&(passwordatm.length>0)){return true;}return false;}//登录事件function login(){var account = document.getElementById("account").value;var passwordatm = document.getElementById("passwordatm").value;console.log(typeof account);console.log(passwordatm);if(isNaNAccount(account)){alert("卡号必须是数字");return;}if(!(isNaNAccountAndPwd(account,passwordatm))){alert("卡号和密码都不能为空");return;}if((i>0) && (account=="123456789")&&(passwordatm="123")){window.location.href="http://127.0.0.1:8020/reviewJS/DOM%E6%93%8D%E4%BD%9C/ATMindex.html?__hbt=1512374587088";}else{if(i==0){alert("你的账号已被锁定！");return;}alert("你还剩"+i+"次机会！");i--;return ;}}
</script>
ATM机主页
实现了取款，存款的操作
取款的金额超过余额，将有错误提示，不允许操作
<!DOCTYPE html>
<html><head><meta charset="UTF-8"><title></title></head><style type="text/css">div{width: 300px;height:200px;margin: 0 auto;border: 1px solid black;border-radius: 5px;text-align: center;}p{font-size: 20px;text-align: left;}input{width: 150px;height:20px;}button{border: 0px;padding: 5px;background-color: green;color: white;}</style><body><div><p><label>余额：</label><input type="text" id="balance" value="2000.00" disabled="disabled"></p><p><label>存款：</label><input type="text" id="deposit"> <button onclick="deposit()">存款</button></p><p><label>取款：</label><input type="text" id="withdraw"> <button onclick="withDraw()">取款</button></p></div></body>
</html><script>//输入的是否为数字function isNumber(number){return isNaN(number);}//存款操作function deposit(){var balance = parseFloat(document.getElementById("balance").value);var deposit = document.getElementById("deposit").value;if(!deposit.length>0){alert("请输入你要存款的金额..");return;}if(isNumber(deposit)){alert("请输入数字！");return;}balance += parseFloat(deposit);document.getElementById("balance").value = balance;}//取款操作function withDraw(){var balance = parseFloat(document.getElementById("balance").value);console.log(typeof balance);var withdraw =document.getElementById("withdraw").value;if(!withdraw.length>0){alert("请输入你要取款的金额..");return;}if(isNumber(withdraw)){alert("请输入数字！");return;}if(parseFloat(withdraw) >balance){alert("余额不足请重新输入！");return;}balance -=withdraw;document.getElementById("balance").value = balance;}
</script>
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