例 2.1（trimSystemApi.html）
<html>
<head>
<title>$.trim()</title>
<script language="javascript" src="jquery.min.js"></script>
<script language="javascript">
/*jQuery.trim(str)
去掉字符串起始和结尾的空格。
*/
var sString = " 12345 ";
/* if the following $ is changed to jQuery, the result is the same. */
sString = $.trim(sString);
//sString = jQuery.trim(sString);
alert(sString.length);
</script>
</head>
<body>
</body>
</html>
更多内容请见原文，文章转载自：https://blog.csdn.net/qq_44594371/article/details/103062778