js去除字符串两边的空格

var str = " 删除左右两端的空格 "
str.replace(/(^\s*)|(\s*$)/g, "");
 
var str = " 删除左边的空格 "
str.replace(/(^\s*)/g,"");
 
var str = " 删除右边的空格 "
str.replace(/(\s*$)/g,"");