对象值的笛卡尔积（到数组）

Question

假设我有const item = {  "Key1": "Value1",  "Key2": ["Value2", "Value3"]}如何将其转换为[["Value1","Value2"],["Value1","Value3"]] ？我的做法是：let array = [];for (let i of item.Key2){  array.push([item.Key1,i])}只是想知道还有没有更短的方法？

Answer 1

// What question mentions

const item = {

  "Key1": "Value1",

  "Key2": ["Value2", "Value3"]

}

let res = item.Key2.map(i => [item.Key1, i])

console.log(res)

// What the world wants!

const item = {

  "Key1": ["ValueA", "ValueB"],

  "Key2": ["Value1", "Value2"]

}

res = item.Key1.reduce((acc, i1) => acc.concat(item.Key2.map(i2 => [i1, i2])), [])

console.log(res)

Answer 2

您可以构建笛卡尔积。

const

    item = { Key1: "Value1", Key2: ["Value2", "Value3"] },

    values = Object.values(item).map(v => [].concat(v)),

    result = values.reduce((a, b) => a.reduce((r, v) => r.concat(b.map(w => [].concat(v, w))), []));

console.log(result);

Answer 3

const item = { Key1: "Value1", Key2: ["Value2", "Value3"]};

let target = item.Key2.reduce((i, _) => {

  i.push([item.Key1, _]);

  return i;

}, []);

console.log(target)