javascript - Lodash:在自己的数组中找到所有具有特定值的键

Question

我正在使用 lodash 对下面的数组执行以下任务:

let map = {
   "John": ["math", "physics", "chem"],
   "Lisa": ["bio", "chem", "history"],
   "Emily": ["math", "history", "javascript"];
}

使用 lodash，如何返回其数组中值为“javascript”的键，在本例中为 Emily？

我在用

_.keys(_.pickBy(map, e => {
    return (e == 'javascript');
}))

但这似乎不起作用

Answer 1

您可以使用findKey 和includes 方法来查找 key 。

let map = {
  "John": ["math", "physics", "chem"],
  "Lisa": ["bio", "chem", "history"],
  "Emily": ["math", "history", "javascript"]
}

const result = _.findKey(map, e => _.includes(e, 'javascript'))
console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.js"></script>

要匹配值包含元素的多个键，您可以使用 pickBy 方法来过滤属性，然后获取键。

let map = {
  "John": ["math", "physics", "chem"],
  "Lisa": ["bio", "chem", "history", "javascript"],
  "Emily": ["math", "history", "javascript"]
}

const result = _.keys(_.pickBy(map, e => _.includes(e, "javascript")))
console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.js"></script>