JavaScript to get array of keys from array of objects

Question

I have this array, each object in the array has one key only:

[{ "hello": "value1" }, { "there": "value2" }, { "everybody": "value3" }]

I want to extract all the keys into an array such that the result I want is:

["hello", "there", "everybody"]

What's a succinct way of doing this in Lodash or vanilla JavaScript (preferably ES6)?

Answer 1

Combine to a single object using Object#assign, and retrieve the keys from the object using Object#keys:

const arr = [{ "hello": "value1" }, { "there": "value2" }, { "everybody": "value3" }];

const keys = Object.keys(Object.assign({}, ...arr));

console.log(keys);

And the ES5 version using lodash's _.assign() with _.spread() to combine to a single object, and _.keys() to get the keys:

var arr = [{ "hello": "value1" }, { "there": "value2" }, { "everybody": "value3" }];

var keys = _.keys(_.spread(_.assign)(arr))

console.log(keys);
    
    

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