Perform a deeply recursive reduce on a JSON-encodable JavaScript Object hierarchy.

deep-reduce.js

/**
 * Perform a deeply recursive reduce on a set of JSON, or a JSON-encodable Object hierarchy.
 *
 * @param  {Array|Object} collection
 * @param  {Function}     fn
 * @param  {*}            memo
 * @return {*}
 */
function deepReduce(collection, fn, memo) {

  /**
   * @inner
   * @param  {*} value
   * @param  {String[]} path
   * @return {*}
   */
  function iterator(value, path) {
    var type = Object.prototype.toString.call(value);
    memo = fn(memo, value, path);
    if (type === '[object Array]') {
      for (var i = 0, len = value.length; i < len; i++) {
        iterator(value[i], path.concat(i));
      }
    } else if (type === '[object Object]') {
      for (var key in value) {
        iterator(value[key], path.concat(key));
      }
    }
    return memo;
  }

  return iterator(collection, []);

}

deep-reduce.ts

/*
 * Equivalent version in TypeScript
 */

import { each, isArray, isObject } from 'lodash';

export function deepReduce<In, Out>(
  reducer: (accumulator: Out, value: any, path: Array<string | number>) => Out,
  collection: In,
  accumulator: Out,
): Out {
  const iterator = <T>(value: T, paths: Array<string | number>) => {
    accumulator = reducer(accumulator, value, paths);
    if (isArray(value) || isObject(value)) {
      each(value, (innerValue, innerKey) =>
        iterator<typeof innerValue>(innerValue, paths.concat(innerKey)),
      );
    }
  };
  iterator<In>(collection, []);
  return accumulator;
}

JavaScript Deep Reduce

Performs a deeply recursive reduce on a JSON-encodable JavaScript Object hierarchy.

Example

The following iterator flattens a deeply nested JavaScript object hierarchy into a single object.

deepReduce(data, function(memo, value, path) {
  memo[path.join('.')] = value;
  return memo;
}, {});

Input

When data is;

var data = [{
  "id": 0,
  "isActive": false,
  "balance": "$1,994.61",
  "age": 20,
  "eyeColor": "brown",
  "name": "Lesley Ford",
  "company": "NEUROCELL",
  "email": "[email protected]",
  "phone": "+1 (888) 558-3380",
  "tags": [
    "amet",
    "nostrud",
    "ea",
    "minim"
  ],
  "friends": [{
    "id": 0,
    "name": "Key Silva"
  }, {
    "id": 1,
    "name": "Weiss Combs"
  }]
}, {
  "id": 1,
  "isActive": false,
  "balance": "$2,051.93",
  "age": 24,
  "eyeColor": "blue",
  "name": "Reid Carson",
  "company": "JASPER",
  "email": "[email protected]",
  "phone": "+1 (852) 474-2176",
  "tags": [
    "deserunt",
    "laboris",
    "laborum",
    "Lorem"
  ],
  "friends": [{
    "id": 0,
    "name": "Lee Ingram"
  }, {
    "id": 1,
    "name": "Martha Mcintyre"
  }]
}];

Output

Our example produces the following output;

{
  "0": {
    "id": 0,
    "isActive": false,
    "balance": "$1,994.61",
    "age": 20,
    "eyeColor": "brown",
    "name": "Lesley Ford",
    "company": "NEUROCELL",
    "email": "[email protected]",
    "phone": "+1 (888) 558-3380",
    "tags": [
      "amet",
      "nostrud",
      "ea",
      "minim"
    ],
    "friends": [{
      "id": 0,
      "name": "Key Silva"
    }, {
      "id": 1,
      "name": "Weiss Combs"
    }]
  },
  "1": {
    "id": 1,
    "isActive": false,
    "balance": "$2,051.93",
    "age": 24,
    "eyeColor": "blue",
    "name": "Reid Carson",
    "company": "JASPER",
    "email": "[email protected]",
    "phone": "+1 (852) 474-2176",
    "tags": [
      "deserunt",
      "laboris",
      "laborum",
      "Lorem"
    ],
    "friends": [{
      "id": 0,
      "name": "Lee Ingram"
    }, {
      "id": 1,
      "name": "Martha Mcintyre"
    }]
  },
  "": [{
    "id": 0,
    "isActive": false,
    "balance": "$1,994.61",
    "age": 20,
    "eyeColor": "brown",
    "name": "Lesley Ford",
    "company": "NEUROCELL",
    "email": "[email protected]",
    "phone": "+1 (888) 558-3380",
    "tags": [
      "amet",
      "nostrud",
      "ea",
      "minim"
    ],
    "friends": [{
      "id": 0,
      "name": "Key Silva"
    }, {
      "id": 1,
      "name": "Weiss Combs"
    }]
  }, {
    "id": 1,
    "isActive": false,
    "balance": "$2,051.93",
    "age": 24,
    "eyeColor": "blue",
    "name": "Reid Carson",
    "company": "JASPER",
    "email": "[email protected]",
    "phone": "+1 (852) 474-2176",
    "tags": [
      "deserunt",
      "laboris",
      "laborum",
      "Lorem"
    ],
    "friends": [{
      "id": 0,
      "name": "Lee Ingram"
    }, {
      "id": 1,
      "name": "Martha Mcintyre"
    }]
  }],
  "0.id": 0,
  "0.isActive": false,
  "0.balance": "$1,994.61",
  "0.age": 20,
  "0.eyeColor": "brown",
  "0.name": "Lesley Ford",
  "0.company": "NEUROCELL",
  "0.email": "[email protected]",
  "0.phone": "+1 (888) 558-3380",
  "0.tags": [
    "amet",
    "nostrud",
    "ea",
    "minim"
  ],
  "0.tags.0": "amet",
  "0.tags.1": "nostrud",
  "0.tags.2": "ea",
  "0.tags.3": "minim",
  "0.friends": [{
    "id": 0,
    "name": "Key Silva"
  }, {
    "id": 1,
    "name": "Weiss Combs"
  }],
  "0.friends.0": {
    "id": 0,
    "name": "Key Silva"
  },
  "0.friends.0.id": 0,
  "0.friends.0.name": "Key Silva",
  "0.friends.1": {
    "id": 1,
    "name": "Weiss Combs"
  },
  "0.friends.1.id": 1,
  "0.friends.1.name": "Weiss Combs",
  "1.id": 1,
  "1.isActive": false,
  "1.balance": "$2,051.93",
  "1.age": 24,
  "1.eyeColor": "blue",
  "1.name": "Reid Carson",
  "1.company": "JASPER",
  "1.email": "[email protected]",
  "1.phone": "+1 (852) 474-2176",
  "1.tags": [
    "deserunt",
    "laboris",
    "laborum",
    "Lorem"
  ],
  "1.tags.0": "deserunt",
  "1.tags.1": "laboris",
  "1.tags.2": "laborum",
  "1.tags.3": "Lorem",
  "1.friends": [{
    "id": 0,
    "name": "Lee Ingram"
  }, {
    "id": 1,
    "name": "Martha Mcintyre"
  }],
  "1.friends.0": {
    "id": 0,
    "name": "Lee Ingram"
  },
  "1.friends.0.id": 0,
  "1.friends.0.name": "Lee Ingram",
  "1.friends.1": {
    "id": 1,
    "name": "Martha Mcintyre"
  },
  "1.friends.1.id": 1,
  "1.friends.1.name": "Martha Mcintyre"
}

Thanks mate. I was looking for something like this, saved my day!