Merging two or more arrays by making unique by a list of keys.

mergingArrays.js

/**
 * Merge two or more same structured arrays of objects
 * and make them unique by user provided keys.
 *
 * @author Sajeeb Ahamed
 */

const mergeArrays = (...arrays) => {
    // Consider the last argument as the keys
	const keys = arrays.pop();
	const result = {};

	arrays.forEach(array =>
		array.forEach(item => {
			const key = keys.map(i => item[i]).join('-');
			result[key] = item;
		})
	);

	return Object.values(result);
};

const array1 = [{ name: 'John Doe', age: 25 },{ name: 'Alice', age: 25 },{ name: 'Bob', age: 20 }];
const array2 = [{ name: 'John Joe', age: 25 },{ name: 'Alice', age: 30 },{ name: 'Bob', age: 20 }];

const output = mergeArrays(array1, array2, ['age']);
console.log(output);