cayasso/flatten.js

## flatten.js
/**
 * Takes a deeply nested object, `source`, and returns an object with
 * dot-separated paths pointing to all primitive values from `source`.
 */

const keys = Object.keys
const isArray = Array.isArray

function flatten(source) {
	let total = {}

  return keys(source).reduce((acc, key) => {

    // If its an array then convert it to an object
    if (isArray(source[key])) {
      source[key] = source[key].reduce((arr, val, i) => {
        arr[i] = val
        return arr
      }, {})
    }

    if (_.isPlainObject(source[key])) {
      const res = flatten(source[key])

      // Iterate over the response to get the final key/val
      total = keys(res).reduce((t, k) => {

        // This account for only promitives
        if (!_.isPlainObject(res[k])) {
          t[`${key}.${k}`] = res[k]
        }

        return t
      }, total)

    } else {
      acc[key] = source[key]
    }

    return acc
  }, total)
}

## index.html
<!DOCTYPE HTML>
<html>
  <head>
    <title>Elastic Coding Exercise</title>
    <link href="https://cdnjs.cloudflare.com/ajax/libs/mocha/2.2.5/mocha.css" rel="stylesheet" />
  </head>
  <body>
    <div id="mocha"></div>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/mocha/2.2.5/mocha.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/chai/2.3.0/chai.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>
    <script src="flatten.js"></script>
    <script src="test.flatten.js"></script>
  </body>
</html>

## test.flatten.js
mocha.setup('bdd');
const expect = chai.expect;

describe('flatten()', function () {
	it('should flatten a simple nested object', function () {
		const source = {
			foo: {
				bar: 1
			}
		};

		const expected = {
			'foo.bar': 1
		};

		expect(flatten(source)).to.deep.equal(expected);
	});

	it('should flatten an object with nested arrays', function () {
		const source = {
			foo: [{
				bar: 1
			}, {
				bar: 2
			}]
		};

		const expected = {
			'foo.0.bar': 1,
			'foo.1.bar': 2
		};

		expect(flatten(source)).to.deep.equal(expected);
	});

	it('should flatten a complex nested object', function () {
		const source = {
			a: 1,
			b: {
				c: true,
				d: {
					e: 'foo'
				}
			},
			f: false,
			g: ['red', 'green', 'blue'],
			h: [{
				i: 2,
				j: 3
			}]
		};

		const expected = {
			'a': 1,
			'b.c': true,
			'b.d.e': 'foo',
			'f': false,
			'g.0': 'red',
			'g.1': 'green',
			'g.2': 'blue',
			'h.0.i': 2,
			'h.0.j': 3
		};

		expect(flatten(source)).to.deep.equal(expected);
	});
});

mocha.run();
	/**
	* Takes a deeply nested object, `source`, and returns an object with
	* dot-separated paths pointing to all primitive values from `source`.
	*/

	const keys = Object.keys
	const isArray = Array.isArray

	function flatten(source) {
	let total = {}

	return keys(source).reduce((acc, key) => {

	// If its an array then convert it to an object
	if (isArray(source[key])) {
	source[key] = source[key].reduce((arr, val, i) => {
	arr[i] = val
	return arr
	}, {})
	}

	if (_.isPlainObject(source[key])) {
	const res = flatten(source[key])

	// Iterate over the response to get the final key/val
	total = keys(res).reduce((t, k) => {

	// This account for only promitives
	if (!_.isPlainObject(res[k])) {
	t[`${key}.${k}`] = res[k]
	}

	return t
	}, total)

	} else {
	acc[key] = source[key]
	}

	return acc
	}, total)
	}
	<!DOCTYPE HTML>
	<html>
	<head>
	<title>Elastic Coding Exercise</title>
	<link href="https://cdnjs.cloudflare.com/ajax/libs/mocha/2.2.5/mocha.css" rel="stylesheet" />
	</head>
	<body>
	<div id="mocha"></div>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/mocha/2.2.5/mocha.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/chai/2.3.0/chai.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>
	<script src="flatten.js"></script>
	<script src="test.flatten.js"></script>
	</body>
	</html>
	mocha.setup('bdd');
	const expect = chai.expect;

	describe('flatten()', function () {
	it('should flatten a simple nested object', function () {
	const source = {
	foo: {
	bar: 1
	}
	};

	const expected = {
	'foo.bar': 1
	};

	expect(flatten(source)).to.deep.equal(expected);
	});

	it('should flatten an object with nested arrays', function () {
	const source = {
	foo: [{
	bar: 1
	}, {
	bar: 2
	}]
	};

	const expected = {
	'foo.0.bar': 1,
	'foo.1.bar': 2
	};

	expect(flatten(source)).to.deep.equal(expected);
	});

	it('should flatten a complex nested object', function () {
	const source = {
	a: 1,
	b: {
	c: true,
	d: {
	e: 'foo'
	}
	},
	f: false,
	g: ['red', 'green', 'blue'],
	h: [{
	i: 2,
	j: 3
	}]
	};

	const expected = {
	'a': 1,
	'b.c': true,
	'b.d.e': 'foo',
	'f': false,
	'g.0': 'red',
	'g.1': 'green',
	'g.2': 'blue',
	'h.0.i': 2,
	'h.0.j': 3
	};

	expect(flatten(source)).to.deep.equal(expected);
	});
	});

	mocha.run();