jquery
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<input type="text" />
<script src="http://static.dtao.org/libs/jquery/1.11.2/jquery.js"></script>
<script>
!function () {
$('#J_BankCard').on('keyup mouseout input',function(){
var $this = $(this),
v = $this.val();
/\S{5}/.test(v) && $this.val(v.replace(/\s/g,'').replace(/(.{4})/g, "$1 "));
});
}();
</script>
</body>
</html>
原生
!function () {
document.getElementById('bankCard').onkeyup = function (event) {
var v = this.value;
if(/\S{5}/.test(v)){
this.value = v.replace(/\s/g, '').replace(/(.{4})/g, "$1 ");
}
};
}();
转自：http://www.dtao.org/archives/472