How to extract keys as arrays from an array of objects?

Question

I need to extract, from this array

const mylist = [
            {
               "key": "",
               "doc_count": 3
            },
            {
               "key": "IT",
               "doc_count": 1
            }
         ]

an array of the values of key:

["", "IT"]

Today I use a simplistic approach

finalList = []
_.forEach(myList, function (element) {
  finalList.push(element.key)
})

but I saw that lodash has several methods which are almost the ones for my case: _.zip/_.unzip, _.fromPairs/_.toPairs and _.zipObject

Is there a way to simplify this code based on a lodash method?

Ori Drori · Accepted Answer · 2017-08-08 13:14:13Z

1

You can do this easily without lodash by using Array#map to extract the keys to an array:

const mylist = [{"key":"","doc_count":3},{"key":"IT","doc_count":1}];

const result = mylist.map(({ key }) => key);

console.log(result);

If you already have lodash in your project you can use _.map():

const mylist = [{"key":"","doc_count":3},{"key":"IT","doc_count":1}];

const result = _.map(mylist, 'key');

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

answered Aug 8, 2017 at 13:14

Ori Drori

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