<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>focus</title>
<style>
.demo {
background-color: orange;
}
</style>
</head>
<body>
<button id="btn">显示输入框</button>
<script type="text/javascript">
const btn = document.getElementById("btn")
btn.onclick = () => {
const input = document.createElement('input')
input.className = 'demo'
input.value = 99
input.onclick = ()=>alert(1)
document.body.appendChild(input)
input.parentElement.style.backgroundColor = "skyblue"
input.focus()
}
</script>
</body>
</html>