js文字列の前と後ろの空の文字列を削除

var str1 = "   hello world   ";
var str2 = str1.trim();
console.log(str1);//    "   hello world   "
console.log(str2);//      "hello world"

function trimStr(str){
   var re = /^\s+|\s+$/g; // |     \s      +                                
  return str.replace(re,''); //       
}
var str1 = "   hello world   ";
var str2 = trimStr(str1);
console.log(str1);//    "   hello world   "
console.log(str2);//      "hello world"