用JS去掉前后空格或中间空格大全

//去除字符串前后所有空
 function Trim(str)

         { 

             return str.replace(/(^\s*)|(\s*$)/g, ""); 

     }
//在字符串原型上添加方法也可
String.prototype.Trim = function()
{
    return this.replace(/(^\s*)|(\s*$)/g, "");
}

//去除字符串前面空格
String.prototype.LTrim = function()
{
     return this.replace(/(^\s*)/g, "");
}

//去除字符串后面空格

String.prototype.RTrim = function()
{
    return this.replace(/(\s*$)/g, "");
}

//去除前面空格
function trim(mystr){
   while ((mystr.indexOf(" ")==0) && (mystr.length>1)){
    mystr=mystr.substring(1,mystr.length);
   }

  //去除后面空格
    while ((mystr.lastIndexOf(" ")==mystr.length-1)&&(mystr.length>1)){
      mystr=mystr.substring(0,mystr.length-1);
   }

  if (mystr==" "){
    mystr="";
   }
    return mystr;
}

str = str.replace(/[ ]/g,""); //替换所有空白
//刪除所有空白
function allTrim(s)
{
    var s1 = lTrim(s);
    return (rTrim(s1));
}
//刪除左方空白(含全形空白)
function lTrim(s)
{
    s = "" + s;
    var len = s.length;
    var pos = 0;
    var s1 = "";

    while (pos < len)
    {
        var chr = s.substring(pos, pos + 1);
        if (chr == " " || chr == "" || chr == "　")
            pos = pos + 1;
        else
            return (s.substring(pos,len));
    }
    return s1;
}
//刪除右方空白(含全形空白)
function rTrim(s)
{
    s = "" + s;
    var len = s.length;
    var pos = len -1;
    var s1 = "";
    var i = 0;

    while (pos >= 0)
    {
        var chr = s.substring(pos, s.length - i);
        if (chr == " " || chr == "" || chr == "  ")
            pos = pos - 1;
        else
            return (s.substring(0, pos +1));
        i++;
    }
    return s1;
}
//去掉字符串中間多餘空白（保留一個空白）
function middleTrim(str)
{
    var repStr="";
    for(var i=0;i<str.length;i++)
    {
        if(str.substring(i,i+1)!=" ")
           repStr=repStr+str.substring(i,i+1);
        else
        {
            if(repStr.substring(repStr.length-1,repStr.length)!=" ")
            {
                repStr=repStr+" ";
            }
        }
    }
    return repStr;
}

 function Trim(str,is_global)

        {

            var result;

            result = str.replace(/(^\s+)|(\s+$)/g,"");

            if(is_global.toLowerCase()=="g")

            {

                result = result.replace(/\s/g,"");

             }

            return result;

}