使用标题破坏

Question

我已经用 destructing 回答了几个问题，我只是想把这个提升到一个新的水平

我不想在这个例子中使用 reduce，而是尽可能使用纯破坏

因此数据的第一行包含 object 的属性名称，我怎样才能将其用作 DRY

即我希望

const obj = data.slice(1).map((titles) => ({ titles }) )

或类似

所以这行得通，但我还漏了一步：

const data = [
    ["fruits","frozen","fresh","rotten"],
    ["apples",884,494,494],
    ["oranges",4848,494,4949],
    ["kiwi",848,33,33]
]
const titles = data[0]; // not used below but I want to use it
const obj = data.slice(1).map(([fruits,frozen,fresh,rotten]) => ({ fruits,frozen,fresh,rotten }) )
console.log(obj)

Answer 1

你可以使用reduce，但你不能真正破坏...

const data = [
    ["fruits","frozen","fresh","rotten"],
    ["apples",884,494,494],
    ["oranges",4848,494,4949],
    ["kiwi",848,33,33]
]
const titles = data[0];
const obj = data.slice(1).map((row) => titles.reduce((agg, cur, index) => {
   agg[cur] = row[index];
   return agg;
}, {}));
console.log(obj)

Answer 2

您可以映射对象的条目。

const
    data = [["fruits", "frozen", "fresh", "rotten"], ["apples", 884, 494, 494], ["oranges", 4848, 494, 4949], ["kiwi", 848, 33, 33]],
    mapWith = keys => values => Object.fromEntries(keys.map((k, i) => [k, values[i]])),
    getArray = ([keys, ...data]) => data.map(mapWith(keys)),
    array = getArray(data);

console.log(array);

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旧的更简单的例子

const data = [
  ["fruits", "frozen", "fresh", "rotten"],
  ["apples", 884, 494, 494],
  ["oranges", 4848, 494, 4949],
  ["kiwi", 848, 33, 33]
]
const titles = data[0];

const obj = data.slice(1).map(
  arr => Object.fromEntries(
    titles.map( 
      (t, i) => [t, arr[i]] 
    )
  )
);

console.log(obj);

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Answer 3

您可以创建 zip 的柯里化版本，它与 Object.fromEntries 类似，不同之处在于它不采用对，而是键列表和值列表以及基于索引：

zip(['a','b'], [1,2]);
//=> {a: 1, b: 2})

因为它是柯里化的，所以您可以在地图中使用它并避免硬编码标题：

const data = [
    ["fruits","frozen","fresh","rotten"],
    ["apples",884,494,494],
    ["oranges",4848,494,4949],
    ["kiwi",848,33,33]
]

const zip =
  keys =>
    values =>
      Object.fromEntries
        ( keys.map((k, i) => [k, values[i]])
        );
        
const from_csv =
  ([titles, ...rows]) =>
    rows.map(zip(titles));

console.log(
  from_csv(data)
);

Answer 4

const data = [
    ["fruits","frozen","fresh","rotten"],
    ["apples",884,494,494],
    ["oranges",4848,494,4949],
    ["kiwi",848,33,33]
];
const [titles, ...rest] = data;
const obj = rest.map((xs) => {
  const o = {};
  xs.forEach((x,i) => o[titles[i]] = x);
  return o;
});
console.log(obj);

使用标题破坏

Destruct using titles

javascript

arrays

destructuring