Flatten array with objects into 1 object

Use Object.assign:

let merged = Object.assign(...arr); // ES6 (2015) syntax

var merged = Object.assign.apply(Object, arr); // ES5 syntax

Note that Object.assign is not yet implemented in many environment and you might need to polyfill it (either with core-js, another polyfill or using the polyfill on MDN).

You mentioned lodash, so it's worth pointing out it comes with a _.assign function for this purpose that does the same thing:

 var merged = _.assign.apply(_, [{ a: 1 }, { b: 2 }, { c: 3 }]);

But I really recommend the new standard library way.

With lodash, you can use merge():

var arr = [ { a: 1 }, { b: 2 }, { c: 3 } ];
_.merge.apply(null, [{}].concat(arr));
// → { a: 1, b: 2, c: 3 }

If you're doing this in several places, you can make merge() a little more elegant by using partial() and spread():

var merge = _.spread(_.partial(_.merge, {}));
merge(arr);
// → { a: 1, b: 2, c: 3 }