本文介绍了一种使用JavaScript实现字符串左右两端去除空格的方法。通过定义ltrim()、rtrim()和trim()三个函数，可以有效地移除字符串开头、结尾及同时两头的空白字符。这些函数采用简单的while循环和substring方法来逐个检查并删除字符。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
</HEAD>
<BODY>
<INPUT TYPE="text" NAME="" id="t"><button onclick="a()"/>
</BODY>
<SCRIPT LANGUAGE="JavaScript">
<!--
function a()
{
var t = document.getElementById("t").value;
alert(ltrim(t).length);
}
//从右往左去空格
function rtrim(stringObj)
{
while (stringObj.charCodeAt(stringObj.length - 1) == 32)
{
stringObj = stringObj.substring(0,stringObj.length - 1);
}
return stringObj;
}
//从左往右去空格
function ltrim(stringObj)
{
while (stringObj.charCodeAt(0) == 32)
{
stringObj = stringObj.substring(1,stringObj.length);
}
return stringObj;
}
//去字符串左右两边的空格(中间的空格不能去)
function trim(stringObj)
{
return(ltrim(rtrim(stringObj)));
}
//-->
</SCRIPT>
</HTML>
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META NAME="Generator" CONTENT="EditPlus">
<META NAME="Author" CONTENT="">
<META NAME="Keywords" CONTENT="">
<META NAME="Description" CONTENT="">
</HEAD>
<BODY>
<INPUT TYPE="text" NAME="" id="t"><button onclick="a()"/>
</BODY>
<SCRIPT LANGUAGE="JavaScript">
<!--
function a()
{
var t = document.getElementById("t").value;
alert(ltrim(t).length);
}
//从右往左去空格
function rtrim(stringObj)
{
while (stringObj.charCodeAt(stringObj.length - 1) == 32)
{
stringObj = stringObj.substring(0,stringObj.length - 1);
}
return stringObj;
}
//从左往右去空格
function ltrim(stringObj)
{
while (stringObj.charCodeAt(0) == 32)
{
stringObj = stringObj.substring(1,stringObj.length);
}
return stringObj;
}
//去字符串左右两边的空格(中间的空格不能去)
function trim(stringObj)
{
return(ltrim(rtrim(stringObj)));
}
//-->
</SCRIPT>
</HTML>
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