<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
<title></title>
<script src="jquery-1.10.1.min.js" ></script>
</head>
<body>
<input type="text" id="alterNumber" style="width: 300px;"/>
<script>
$(function() {
//难点不是插入空格,而是修正光标的位置,这个只支持IE9+
//可用于银行卡号
$('#alterNumber').on('keyup', function(e) {
//只对输入数字时进行处理
if((e.which >= 48 && e.which <= 57) || (e.which >= 96 && e.which <= 105 )){
//获取当前光标的位置
var caret = this.selectionStart;
//获取当前的value
var value = this.value;
//从左边沿到坐标之间的空格数
var sp = (value.slice(0, caret).match(/\s/g) || []).length;
//去掉所有空格
var nospace = value.replace(/\s/g, '');
//重新插入空格
var curVal = this.value = nospace.replace(/(\d{4})/g, "$1 ").trim();
//从左边沿到原坐标之间的空格数
var curSp = (curVal.slice(0, caret).match(/\s/g) || []).length;
//修正光标位置
this.selectionEnd = this.selectionStart = caret + curSp - sp;
}
})
})
</script>
</body>
</html>
效果图: