Lodash - unionWith method

Syntax

_.unionWith([arrays], [comparator])

This method is like _.union except that it accepts comparator which is invoked to compare elements of arrays. Result values are chosen from the first array in which the value occurs. The comparator is invoked with two arguments: (arrVal, othVal).

Arguments

• [arrays] (...Array) − The array to inspect.

• [comparator] (Function) − The comparator invoked per element.

Output

• (Array) − Returns the new array of combined values.

Example

var _ = require('lodash');
var objects = [{ 'x': 1, 'y': 1 }, { 'x': 1, 'y': 2 }];
var others = [{ 'x': 2, 'y': 1 }, { 'x': 1, 'y': 2 }];
 
var result = _.unionWith(objects, others, _.isEqual);
console.log(result);

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

Command

\>node tester.js

Output

[ { x: 1, y: 1 }, { x: 1, y: 2 }, { x: 2, y: 1 } ]