Question

问题我有一个Javascript数组，并且尝试以最有效的方式仅返回与特定键匹配的key：value对。

我尝试使用Foreach循环并将每个key：value推送到新数组，但这似乎是一种效率低下的方法，而且过于复杂。

代码

initialArray = [ { friends: [],
    otherFriends: [],
    _id: 5c6c7132f9bf4bdab9c906ff,
    user: 5c65d9438e4a834c8e85dd7d,
    password: '$2b$10$LMFB6CBdwxSAfjog/Uo3t.u/G0GBtzfJnYdpvlrSNchA9.jlNOdAa',
    email: 'sparky2df3dfdfdf2@gmail.com',
    createdAt: 2019-02-19T21:12:18.569Z,
    updatedAt: null,
    online: false,
    __v: 0 },
  { friends: [],
    otherFriends: [],
    _id: 5c6ccd6d3a0dc4e4951c2bee,
    user: 5c65d9438e4a834c8e85dd7e,
    password: '$2b$10$gEAbOAdKyHJfAksr5txUNOudCautRs1w/pubplQKzZ5PefhfOOEhq',
    email: 'fdagssd@gmail.com',
    createdAt: 2019-02-20T03:45:49.703Z,
    updatedAt: null,
    online: false,
    __v: 0 } ]

所需数组

[ 
    { user: 5c65d9438e4a834c8e85dd7d },
    { user: 5c65d9438e4a834c8e85dd7e }
]

当前方法

const newArray = []
initialArray.forEach(element => {
            newArray.push({key: element.user});
        });

如果有人有任何令人惊奇的建议！在此先感谢:)

Answer 1

您可以为user使用destructuring assignment并映射此short hand property。

var initialArray = [{ friends: [], otherFriends: [], _id: '5c6c7132f9bf4bdab9c906ff', user: '5c65d9438e4a834c8e85dd7d', password: '$2b$10$LMFB6CBdwxSAfjog/Uo3t.u/G0GBtzfJnYdpvlrSNchA9.jlNOdAa', email: 'sparky2df3dfdfdf2@gmail.com', createdAt: '2019-02-19T21:12:18.569Z', updatedAt: null, online: false, __v: 0 }, { friends: [], otherFriends: [], _id: '5c6ccd6d3a0dc4e4951c2bee', user: '5c65d9438e4a834c8e85dd7e', password: '$2b$10$gEAbOAdKyHJfAksr5txUNOudCautRs1w/pubplQKzZ5PefhfOOEhq', email: 'fdagssd@gmail.com', createdAt: '2019-02-20T03:45:49.703Z', updatedAt: null, online: false, __v: 0 }] 
    newArray = initialArray.map(({ user }) => ({ user }));

console.log(newArray);

Answer 2

您可以将所需的键保留在数组中，如下所示。

此示例提取两个键值。

var initialArray = [{ friends: [], otherFriends: [], _id: '5c6c7132f9bf4bdab9c906ff', user: '5c65d9438e4a834c8e85dd7d', password: '$2b$10$LMFB6CBdwxSAfjog/Uo3t.u/G0GBtzfJnYdpvlrSNchA9.jlNOdAa', email: 'sparky2df3dfdfdf2@gmail.com', createdAt: '2019-02-19T21:12:18.569Z', updatedAt: null, online: false, __v: 0 }, { friends: [], otherFriends: [], _id: '5c6ccd6d3a0dc4e4951c2bee', user: '5c65d9438e4a834c8e85dd7e', password: '$2b$10$gEAbOAdKyHJfAksr5txUNOudCautRs1w/pubplQKzZ5PefhfOOEhq', email: 'fdagssd@gmail.com', createdAt: '2019-02-20T03:45:49.703Z', updatedAt: null, online: false, __v: 0 }],
    keys = ["user", "email"], // for the desired output in the question remove "email"
    newArray = initialArray.map(o => keys.reduce((a, k) => Object.assign({}, a, {[k]: o[k]}), {}));

console.log(newArray);

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Javascript数组，返回键：具有特定键的值对

2 个答案: