Flatten Int Array

.gitignore

.idea/
node_modules/

README.md

Flatten Int Array

Flatten an arbitrarily nested array of integers.

Prerequisits

NodeJS 8.x.x https://nodejs.org (It comes with NPM!)

Installation

npm i -S this is a demo so don't install it

Tests

Mocha Exports Interface with Babel Register

Run: npm test

NOTES.md

SETUP

Move files prefixed with src_ to a directory named src and remove the prefix.

This is required because Gists do not allow a folder structure and the intention of this Gist is to reflect the structure of an actual production module.

Run npm i

package.json

{
  "name": "flatten-int-array",
  "version": "0.0.0",
  "description": "Flatten an arbitrarily nested array of integers.",
  "main": "src/index.jsx",
  "scripts": {
    "test": "mocha --require resistdesign-babel-register --ui exports ./src/**/*.spec.jsx"
  },
  "repository": {
    "type": "git",
    "url": "git+ssh://git@gist.github.com/2aec3c0bd5bdff24e5019b642f08e150.git"
  },
  "keywords": [
    "JavaScript",
    "ES6",
    "Array",
    "Int",
    "Flatten"
  ],
  "author": "",
  "license": "MIT",
  "bugs": {
    "url": "https://gist.github.com/2aec3c0bd5bdff24e5019b642f08e150"
  },
  "homepage": "https://gist.github.com/2aec3c0bd5bdff24e5019b642f08e150",
  "devDependencies": {
    "expect.js": "^0.3.1",
    "resistdesign-babel-register": "^1.0.1"
  }
}

src_index.jsx

function isInt (value) {
  return Number.isInteger(value);
}

/**
 * Flatten an arbitrarily nested array of integers.
 * @param {Array.<number|Array>} input The array to flatten.
 * @returns {Array.<number>} The flattened array containing only integers.
 * */
export default function flattenIntArray (input) {
  // Always return an array per the documented contract.
  let output = [];

  if (input instanceof Array) {
    input.forEach(value => {
      if (isInt(value)) {
        // Value is an integer
        output.push(value);
      } else {
        // Not an integer
        output = [
          ...output,
          // Flat an clean possibly nested values
          ...flattenIntArray(value)
        ];
      }
    });
  }

  return output;
}

src_index.spec.jsx

import expect from 'expect.js';
import flattenIntArray from './index';

const MOCK_DATA = {
  SIMPLE_INT_ARRAY: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
  MIXED_INT_FLOAT_ARRAY: [47.2, 99, 29.87, 5, 19, 87.0125, 22],
  MIX_TYPE_ARRAY: [{}, 'hello', 21, 'K', 67, [], 19.75, '144', 'next', {}, 4],
  MULTI_NESTED_INT_ARRAY: [
    22,
    77,
    112,
    [
      17,
      4729
    ],
    88,
    [
      77865,
      22425,
      [
        879898,
        3
      ],
      9992
    ],
    17,
    [],
    983472983
  ]
};

module.exports = {
  'flattenIntArray': {
    'should be a function': () => {
      expect(flattenIntArray).to.be.a(Function);
    },
    'should return an array of integers': () => {
      const output = flattenIntArray(
        MOCK_DATA.SIMPLE_INT_ARRAY
      );

      expect(output).to.be.an(Array);
      expect(output).to.have.length(
        MOCK_DATA.SIMPLE_INT_ARRAY.length
      );
      output.forEach((value, index) => {
        const sourceValue = MOCK_DATA.SIMPLE_INT_ARRAY[index];

        expect(value).to.equal(sourceValue);
      });
    },
    'should not include floats in output': () => {
      const output = flattenIntArray(
        MOCK_DATA.MIXED_INT_FLOAT_ARRAY
      );

      expect(output).to.be.an(Array);
      expect(output).to.eql([99, 5, 19, 22]);
    },
    'should not include non-numeric values in output': () => {
      const output = flattenIntArray(
        MOCK_DATA.MIX_TYPE_ARRAY
      );

      expect(output).to.be.an(Array);
      expect(output).to.eql([21, 67, 4]);
    },
    'should flatten an arbitrarily nested array of integers': () => {
      const output = flattenIntArray(
        MOCK_DATA.MULTI_NESTED_INT_ARRAY
      );

      expect(output).to.be.an(Array);
      expect(output).to.eql([
        22,
        77,
        112,
        17,
        4729,
        88,
        77865,
        22425,
        879898,
        3,
        9992,
        17,
        983472983
      ]);
    }
  }
};

If you want, you can generate documentation with something like this: http://documentation.js.org