本来是想用js代码去模拟键盘按下来实现该功能，但是没有实现到。后来想到一种比较笨的方法。局限性是只能这些表单元素只能在同个层面下才能切换。
<!DOCTYPE html>
<html lang="en">
<head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><title>Document</title>
</head>
<body><input type="text" id="i1" onKeyPress="Myenter('i2')"><input type="text" id="i2" onKeyPress="Myenter('i3')"><input type="text" id="i3" onKeyPress="Myenter('i1')"><button class="btn">123</button><script>function Myenter(id) {if (event.keyCode == 13){document.getElementById(id).focus();}}window.onload = function() {}</script>
</body>
</html>
原理很简单啦
