JavaScript如何自定义trim方法

//clear the right and left spacefunction trim(s){  return trimRight(trimLeft(s)); }  //clear the left spacefunction trimLeft(s){  if(s == null) {   return "";  }  var whitespace = new String(" /t/n/r");  var str = new String(s);  if (whitespace.indexOf(str.charAt(0)) != -1) {   var j=0, i = str.length;   while (j < i && whitespace.indexOf(str.charAt(j)) != -1){    j++;   }   str = str.substring(j, i);  }  return str; }  //clear the right space function trimRight(s){  if(s == null) return "";  var whitespace = new String(" /t/n/r");  var str = new String(s);  if (whitespace.indexOf(str.charAt(str.length-1)) != -1){   var i = str.length - 1;   while (i >= 0 && whitespace.indexOf(str.charAt(i)) != -1){    i--;   }   str = str.substring(0, i+1);  }  return str; }