str为要去除空格的字符串:
去除所有空格:
str   =   str.replace(/\s+/g,"");
去除两头空格:
str   =   str.replace(/^\s+|\s+$/g,"");
去除左空格：
str=str.replace( /^\s*/, '');
去除右空格：
str=str.replace(/(\s*$)/g, "");SCRIPT LANGUAGE="JavaScript">
<!--
//出处:网上搜集
// Trim() , Ltrim() , RTrim()
String.prototype.Trim = function()
{
returnthis.replace(/(^\s*)|(\s*$)/g, "");
}
String.prototype.LTrim = function()
{
returnthis.replace(/(^\s*)/g, "");
}
String.prototype.RTrim = function()
{
returnthis.replace(/(\s*$)/g, "");
}
//-->
</SCRIPT>
<input type="text" value="    前后都是空格     " id="space">
<input type="button" value="去前后空格" οnclick="javascript:document.getElementById('space').value=document.getElementById('space').value.Trim();document.getElementById('space').select();">
<input type="button" value="去前空格" οnclick="javascript:document.getElementById('space').value=document.getElementById('space').value.LTrim();document.getElementById('space').select();">
<input type="button" value="去后空格" οnclick="javascript:document.getElementById('space').value=document.getElementById('space').value.RTrim();document.getElementById('space').select();">
<input type="button" value="还原" οnclick="javascript:document.getElementById('space').value='      前后都是空格     ';">
<a href="http://www.yaoasnsi.com" target="_blank">访问yaosansi.com</a> 去除所有空格:
str = str.replace(/\s+/g,"");
去除两头空格:
str = str.replace(/^\s+|\s+$/g,"");
去除空格(TimeSheet用过)
arg0=arg0.replace(/\s+$|^\s+/g,"");

来源：http://www.cnblogs.com/fumj/p/3406420.html