js数组的map()方法操作json数组

利用map方法方便获得对象数组中的特定属性值们。例如下面这个例子：

var users = [
  {name: "张含韵", "email": "[email protected]"},
  {name: "江一燕", "email": "[email protected]"},
  {name: "李小璐", "email": "[email protected]"}
];

var emails = users.map(function (user) { return user.email; });

console.log(emails.join(", ")); // [email protected], [email protected], [email protected]