JavaScript選取(picking)和反選(rejecting)對象的屬性方法

function pick(obj, keys) {
 return keys.map(k => k in obj ? {[k]: obj[k]} : {})
 .reduce((res, o) => Object.assign(res, o), {});
}
const row = {
 'accounts.id': 1,
 'client.name': 'John Doe',
 'bank.code': 'MDAKW213'
};
const table = [
 row,
 {'accounts.id': 3, 'client.name': 'Steve Doe', 'bank.code': 'STV12JB'}
];
pick(row, ['client.name']); // 取到了 client name
table.map(row => pick(row, ['client.name'])); // 取到了一系列 client name

function reject(obj, keys) {
 return Object.keys(obj)
 .filter(k => !keys.includes(k))
 .map(k => ({[k]: obj[k]}))
 .reduce((res, o) => Object.assign(res, o), {});
}
// 或者, 利用 pick
function reject(obj, keys) {
 const vkeys = Object.keys(obj)
 .filter(k => !keys.includes(k));
 return pick(obj, vkeys);
}
reject({a: 2, b: 3, c: 4}, ['a', 'b']); // => {c: 4}