实现效果：
完整输入了“暗号”（一串事先定义好的字符串）时，触发一个事件
关键点：
指定可激发特效的字符串
监听并获取输入的字符
处理输入，在符合条件时，触发事件
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Key Detection</title>
<!-- <script type="text/javascript" src="http://www.cornify.com/js/cornify.js"></script> -->
</head>
<body>
<script>
var pressed = [];
var secretCode = 'QG';
window.addEventListener('keyup',e =>{
// console.log(e.key);
pressed.push(e.key);
// console.log(pressed);
pressed.splice(- secretCode.length - 1,pressed.length - secretCode.length);
console.log(pressed);
if(pressed.join('').includes(secretCode)){
console.log('8023');
}
})
</script>
</body>
</html>