Lodash defaults method

_.defaults(object, [sources])

Assigns own and inherited enumerable string keyed properties of source objects to the destination object for all destination properties that resolve to undefined. Source objects are applied from left to right. Once a property is set, additional values of the same property are ignored.

var _ = require('lodash');
var result = _.defaults({ 'a': 1 }, { 'b': 2 }, { 'a': 3 });
console.log(result);

Save the above program in tester.js. Run the following command to execute this program.

\>node tester.js

{ a: 1, b: 2 }