JS去掉前后空格、判断是否为数字

//JS去掉前后空格函数
function cTrim(sInputString,iType){
      var sTmpStr = ' ';
      var i = -1;
      if(iType == 0 || iType == 1)
      {
            while(sTmpStr == ' '){
                  ++i;
                  sTmpStr = sInputString.substr(i,1);
            }
            sInputString = sInputString.substring(i);
      }
      
      if(iType == 0 || iType == 2)
      {
            sTmpStr = ' ';
            i = sInputString.length;
            while(sTmpStr == ' '){
            --i;
            sTmpStr = sInputString.substr(i,1);
            }
            sInputString = sInputString.substring(0,i+1);
      }
      return sInputString;
}
//判断是否为数字
function is_numeric(num) {
      var reg = /^\-?([1-9]\d*|0)(\.\d+)?$/;
      if( reg.test(num) ){
            return true;
      }else{
            return false;
      }
}