JS - deep map function

Here's a Lodash solution using transform

function deepMap(obj, iterator, context) {    return _.transform(obj, function(result, val, key) {        result[key] = _.isObject(val) /*&& !_.isDate(val)*/ ?                            deepMap(val, iterator, context) :                            iterator.call(context, val, key, obj);    });}_.mixin({   deepMap: deepMap});

Here is a clean ES6 version:

function mapObject(obj, fn) {  return Object.keys(obj).reduce(    (res, key) => {      res[key] = fn(obj[key]);      return res;    },    {}  )}function deepMap(obj, fn) {  const deepMapper = val => typeof val === 'object' ? deepMap(val, fn) : fn(val);  if (Array.isArray(obj)) {    return obj.map(deepMapper);  }  if (typeof obj === 'object') {    return mapObject(obj, deepMapper);  }  return obj;}

Here's my version - slightly lengthy so I expect it can be shortened, but works with arrays and objects and no external dependencies:

function deepMap(obj, f, ctx) {    if (Array.isArray(obj)) {        return obj.map(function(val, key) {            return (typeof val === 'object') ? deepMap(val, f, ctx) : f.call(ctx, val, key);        });    } else if (typeof obj === 'object') {        var res = {};        for (var key in obj) {            var val = obj[key];            if (typeof val === 'object') {                res[key] = deepMap(val, f, ctx);            } else {                res[key] = f.call(ctx, val, key);            }        }        return res;    } else {        return obj;    }}

demo at http://jsfiddle.net/alnitak/0u96o2np/

EDIT slightly shortened now by using ES5-standard Array.prototype.map for the array case