JS左去空格、右去空格和全去空格

<script>        function trim(str){                if(str.length < 1){                        return "";                }                str = rtrim(str);                str = ltrim(str);                if(str==""){                        return "";                }else{                        return str;                }        }         function rtrim(str){                var w_space = String.fromCharCode(32);                var v_length = str.length;                var strTemp = "";                if(v_length < 0){                        return "";                }                var iTemp = v_length -1;                while(iTemp > -1){                        if(str.charAt(iTemp) == w_space){                        }else{                                strTemp = str.substring(0,iTemp +1);                                break;                        }                        iTemp = iTemp-1;                }                 return strTemp;        }         function ltrim(str){                var w_space = String.fromCharCode(32);                if(v_length < 1){                        return"";                }                var v_length = str.length;                var strTemp = "";                                var iTemp = 0;                                while(iTemp < v_length){                        if(str.charAt(iTemp) == w_space){                        }else{                                strTemp = str.substring(iTemp,v_length);                                break;                        }                        iTemp = iTemp + 1;                }                 return strTemp;        }        function check(){                document.login.LoginName.value = trim(document.login.LoginName.value)                return true;        }</script>