js去除字符串兩邊的空格

var str = " 刪除左右兩端的空格 "
str.replace(/(^\s*)|(\s*$)/g, "");
 
var str = " 刪除左邊的空格 "
str.replace(/(^\s*)/g,"");
 
var str = " 刪除右邊的空格 "
str.replace(/(\s*$)/g,"");