Get the keys of a nested object in dot notation.

README.md

string-keys

import keys from 'string-keys'

keys({
  a: 1,
  b: 2,
  c: null,
  d: {
    e: 1
  },
  e: {
    f: {
      a: [
        {
          b: 1
        },
        {
          b: 2,
          g: null
        }
      ]
    }
  }
})

// ['a', 'b', 'c', 'd.e', 'e.f.a.[0].b', 'e.f.a.[1].b', 'e.f.a.[1].g']

.babelrc

{
  "presets": ["es2015"]
}

.gitignore

node_modules/
npm-debug.log

index.js

const getKeys = (values, prefix = '', accumulator = []) => {
  if (!values) return null;

  const isArr = Array.isArray(values);

  return Object.keys(values).reduce((memo, key) => {
    const value = values[key];
    const stringKey = isArr ? `[${key}]` : key;
    const nestedKey = prefix ? `${prefix}.${stringKey}` : stringKey;

    if (value !== null && typeof value === 'object') {
      return getKeys(values[key], nestedKey, memo);
    }

    return memo.concat(nestedKey);
  }, accumulator);
};

export default getKeys;

package.json

{
  "name": "string-keys",
  "description": "Get the keys of a nested object in dot notation.",
  "version": "1.0.0",
  "author": "Luke Karrys <luke@lukekarrys.com>",
  "bugs": {
    "url": "https://gist.github.com/lukekarrys/8e7acddc7ff5bab09851"
  },
  "devDependencies": {
    "babel": "^6.3.13",
    "babel-preset-es2015": "^6.3.13",
    "babel-tape-runner": "^2.0.0",
    "tape": "^4.2.2"
  },
  "homepage": "https://gist.github.com/lukekarrys/8e7acddc7ff5bab09851#file-readme-md",
  "keywords": [
    "dot",
    "keys",
    "notation",
    "object"
  ],
  "license": "MIT",
  "main": "index.js",
  "private": true,
  "repository": {
    "type": "git",
    "url": "git@gist.github.com:8e7acddc7ff5bab09851.git"
  },
  "scripts": {
    "test": "babel-tape-runner test.js"
  }
}

test.js

import test from 'tape';
import keys from './index';

test('Falsy values return null', (t) => {
  t.deepEquals(keys(null), null);
  t.deepEquals(keys(false), null);
  t.end();
});

test('Object works', (t) => {
  const obj = {
    a: 1,
    b: 2,
    c: null
  };
  t.deepEquals(keys(obj), ['a', 'b', 'c']);
  t.end();
});

test('Nested object works', (t) => {
  const obj = {
    a: 1,
    b: 2,
    c: null,
    d: {
      a: 1
    }
  };
  t.deepEquals(keys(obj), ['a', 'b', 'c', 'd.a']);
  t.end();
});

test('Nested object works', (t) => {
  const obj = {
    a: 1,
    b: 2,
    c: undefined,
    d: {
      a: {
        r: 1
      }
    }
  };
  t.deepEquals(keys(obj), ['a', 'b', 'c', 'd.a.r']);
  t.end();
});

test('Nested object works with an array', (t) => {
  const obj = {
    a: 1,
    b: 2,
    c: null,
    d: {
      e: 1
    },
    e: {
      f: {
        a: [
          {
            b: 1
          },
          {
            b: 2,
            g: null
          }
        ]
      }
    }
  };
  t.deepEquals(keys(obj), ['a', 'b', 'c', 'd.e', 'e.f.a.[0].b', 'e.f.a.[1].b', 'e.f.a.[1].g']);
  t.end();
});