Software Solutions Architect - Remote Application

flattenService.js

'use strict';

class FlattenService {
    constructor() {}

    flattenArray(arrayToBeFlattened, flatArray) {
        for (let item of arrayToBeFlattened) {
            if (Array.isArray(item)) {
                this.flattenArray(item, flatArray);
            }
            else {
                flatArray.push(item);
            }
        }
    }
}

module.exports = FlattenService;

flattenService.spec.js

const FlattenService = require('./flattenService');
const chai = require('chai');
const expect = chai.expect;

describe ('flattenArray Works', function () {
    let flattenService = {};

    before (() => {
        flattenService = new FlattenService();
    });

    after (() => {
    });

    it ('can flatten an Array of Arrays of numbers', () => {
        const myArray = [[1,2,[3]],4];
        let flatArray = [];

        flattenService.flattenArray(myArray, flatArray);

        expect(flatArray).to.deep.equal([1,2,3,4]);
    });

    // just tinkering - the requirements didn't specifically ask for distinct, but it's easy to add by 
    //  changing the flatArray.push(item); to if (!flatArray.find((x) => x === item)) { flatArray.push(item); }
    // it ('can flatten an Array of Arrays of numbers into distinct array of numbers', () => {
    //     const myArray = [[1,2,[3,1]],4,2];
    //     let flatArray = [];
    //
    //     flattenService.flattenArray(myArray, flatArray);
    //
    //     expect(flatArray).to.deep.equal([1,2,3,4]);
    // });

    it ('can flatten an Array of Arrays of strings', () => {
        const myArray = [['red','blue',['green']],'yellow'];
        let flatArray = [];

        flattenService.flattenArray(myArray, flatArray);

        expect(flatArray).to.deep.equal(['red','blue','green','yellow']);
    });
});

package.json

{
  "name": "javascripttesting",
  "version": "1.0.0",
  "description": "",
  "main": "src/flattenService.js",
  "scripts": {
    "test": "./node_modules/.bin/mocha src/**/*.spec.js"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {},
  "devDependencies": {
    "chai": "^4.2.0",
    "mocha": "^6.1.4"
  }
}