I'm trying to create a JS object dynamically providing a key and a value. The key is in dot notation, so if a string like car.model.color is provided the generated object would be:
{
car: {
model: {
color: value;
}
}
}
The problem has a trivial solution if the key provided is a simple property, but i'm struggling to make it work for composed keys.
My code:
function (key, value) {
var object = {};
var arr = key.split('.');
for(var i = 0; i < arr.length; i++) {
object = object[arr[i]] = {};
}
object[arr[arr.length-1]] = value;
return object;
}
your slightly modified code
function f(key, value) {
var result = object = {};
var arr = key.split('.');
for(var i = 0; i < arr.length-1; i++) {
object = object[arr[i]] = {};
}
object[arr[arr.length-1]] = value;
return result;
}
In the loop you should set all of the props but the last one.
Next set the final property and all set.
If you're using lodash you could use _.set(object, path, value)
const obj = {}
_.set(obj, "car.model.color", "my value")
console.log(obj)
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.15/lodash.min.js"></script>
Use namespace pattern, like the one Addy Osmani shows: http://addyosmani.com/blog/essential-js-namespacing/
Here's the code, pasted for convenience, all credit goes to Addy:
// top-level namespace being assigned an object literal
var myApp = myApp || {};
// a convenience function for parsing string namespaces and
// automatically generating nested namespaces
function extend( ns, ns_string ) {
var parts = ns_string.split('.'),
parent = ns,
pl, i;
if (parts[0] == "myApp") {
parts = parts.slice(1);
}
pl = parts.length;
for (i = 0; i < pl; i++) {
//create a property if it doesnt exist
if (typeof parent[parts[i]] == 'undefined') {
parent[parts[i]] = {};
}
parent = parent[parts[i]];
}
return parent;
}
// sample usage:
// extend myApp with a deeply nested namespace
var mod = extend(myApp, 'myApp.modules.module2');
function strToObj(str, val) {
var i, obj = {}, strarr = str.split(".");
var x = obj;
for(i=0;i<strarr.length-1;i++) {
x = x[strarr[i]] = {};
}
x[strarr[i]] = val;
return obj;
}
usage: console.log(strToObj("car.model.color","value"));
I would use a recursive method.
var createObject = function(key, value) {
var obj = {};
var parts = key.split('.');
if(parts.length == 1) {
obj[parts[0]] = value;
} else if(parts.length > 1) {
// concat all but the first part of the key
var remainingParts = parts.slice(1,parts.length).join('.');
obj[parts[0]] = createObject(remainingParts, value);
}
return obj;
};
var simple = createObject('simple', 'value1');
var complex = createObject('more.complex.test', 'value2');
console.log(simple);
console.log(complex);
(check the console for the output)
Here's a recursive approach to the problem:
const strToObj = (parts, val) => {
if (!Array.isArray(parts)) {
parts = parts.split(".");
}
if (!parts.length) {
return val;
}
return {
[parts.shift()]: strToObj(parts, val)
};
}
I should suppose to flatten a object, to do this I use this function:
var flatter = function(ob){
var f = {};
for(var i in ob) {
if(typeof ob[i] == 'object') {
var newOb = flatter(ob[i]);
for(var x in newOb) {
f[i+'.'+x] = newOb[x];
}
}else{
f[i] = ob[i];
}
}
return f;
}
works fine. I am getting proper result to applying this object:
var ob = {
"address" : {
"details" : {
"first" : "siva",
"last" : "sankara",
"mam":["mam1","mam2"]
}
}
};
the result is :
reslut : Object {address.details.first: "siva", address.details.last: "sankara", address.details.mam.0: "mam1", address.details.mam.1: "mam2"}
But I am not able to understand the result how i am getting. I understand that, this is oriented with recursion and closure scope - But seaching google I am not get any clear tutorial or article.
Any one help me to understand this my step by step please?
Here is the live demo
Thanks In advance!
function flatter(ob){
'use strict';
var f = {}, //return this
key;
for(key in ob) { //for each key
if (ob.hasOwnProperty(key)) {
if(typeof ob[key] === 'object') { //if value is object
//flatten this object again. Assign result to newOb
var newOb = flatter(ob[key]);
for(var x in newOb) {
f[key + '.' + x] = newOb[x];
}
} else {
f[key] = ob[key];
}
}
}
return f;
}
you can translate this code in something like that
function flatter(ob){
'use strict';
var f = {}, //return this object
key;
for(key in ob) { //for each key
if (ob.hasOwnProperty(key)) {
if(typeof ob[key] === 'object') { //if value is object
var newOb = (function (ob) {
'use strict';
var f = {}, //return this object
key;
for(key in ob) { //for each key
if (ob.hasOwnProperty(key)) {
if(typeof ob[key] === 'object') { //if value is object
var newOb = flatter(ob[key]);
for(var x in newOb) {
f[key + '.' + x] = newOb[x];
}
} else {
f[key] = ob[key];
}
}
}
return f;
}(ob[key]));
for(var x in newOb) {
f[key + '.' + x] = newOb[x];
}
} else {
f[key] = ob[key];
}
}
}
return f;
}
main idea is that every function call can be substituted by body of this function.
Object itself is a recursive structure, because can content objects. If given
{
id: 12345,
name: 'John',
friends: [12346, 75645, 96768]
}
recursion is not needed. Object doesn't contain any objects, so it could be straigtened without additional function call (by the way it is flat). If given
{
id: 12345,
name: {
first: 'John',
last: 'Doe'
},
friends: [12346, 75645, 96768]
}
then object contains object as field. So you can use function flatter where function call is substituted with body of function. If given
{
id: 12345,
name: {
first: 'Helen',
last: {
beforeMarriage: 'Dobsky',
afterMarriage: 'Bobsky'
}
},
friends: [12346, 75645, 96768]
}
then one can't do without 3 function calls. So you can copy body of function three times. But, object can have [infinitely] very deep structure. So number of nested bodies of function is unknown. So, instead of nesting body of function into function recursive call is used.
Recursive function should have at least one exit point to avoid infinite recursion
return f;
in our case. This exit point can be reached because number of fields in object is finite. This is not the only way to solve task. As object looks like tree (a kind of) recursion could be substituted with stack, which keeps complex fields and after processing simple fields return back to stack of objects and treat them in a loop.
Stack implementation. Not beautiful, but works)
function iflatter(input) {
'use strict';
var f = {}, //return this object
key,
stack = [],
ob,
prefix,
name;
stack.push(["", input]);
while (stack.length != 0) {
[prefix, ob] = stack.pop();
for(key in ob) { //for each key
if (ob.hasOwnProperty(key)) {
if (prefix !== "") {
name = prefix + "." + key;
} else {
name = key;
}
if(typeof ob[key] === 'object') {
stack.push([name, ob[key]]);
} else {
f[name] = ob[key];
}
}
}
}
return f;
}
You are passing an Object to flatter(). When the Object has a property that has a value that is an Object itself, it passes that Object to flatter() again, or recursively. See if(typeof ob[i] == 'object')? That means that if ob has property i and its value (gotten as ob[i]) is an Object. Note var flatter = function(){} is equivalent to function flatter(){}.
For example if I have something like so:
var Constants = {
scope:{
namespaceA: { A_X: "TEST_AX" , A_Y: "TEST_AY" },
namespaceN: { N_X: "TEST_NX" , N_Y: "TEST_NY" }
}
_mapping: [],
getMapping: function(){...}
}
var flattenList = flatten(Constants.scope); //returns ["TEST_AX","TEST_AY","TEST_NX","TEST_NY"]
var anotherWayFlattened = flatten(Constants.scope.namespaceA,Constants.scope.namespaceB); //returns same result as above
EDIT: one way would be to iterate over the scope via for-each loop but I was looking for something more elegent?
DOUBLE EDIT: ok I just whipped something up like so:
var flattenedList = (function(list){
var flatList = []
$.each(list,function(i,items){
for(var p in items) flatList.push(items[p]);
})
return flatList;
})([Constants.scope.namespaceA,Constants.scope.namespaceB]);
but was wondering if we can avoid passing in the particular property and just pass in Constants and search for the list of namespaces
[Constants.scope.namespaceA,Constants.scope.namespaceB]
I'm wondering why you pass the sub-objects explicitly in an array. Why not just pass the whole Constants.scope object?
var flattenedList = (function(obj){
var flatList = []
for (var prop in obj) {
var items = obj[prop];
for (var p in items)
flatList.push(items[p]);
}
return flatList;
})(Constants.scope);
From your comment it looks like you wanted this:
var flattenedList = (function(obj, test){
var flatList = []
for (var prop in obj) {
if (!test(prop))
continue;
var items = obj[prop];
for (var p in items)
flatList.push(items[p]);
}
return flatList;
})(Constants, function(name) {
return name.substr(0, 9) == "namespace";
// or maybe
return /^namespace[A-Z]$/.test(name);
});
if you wanted to recurse to any (non cyclical!) depth, you could do this :
function flattenList(list, accumulator){
accumulator = accumulator || [];
for(var p in list){
if(list.hasOwnProperty(p)) {
if(typeof list[p] === "string") {
accumulator.push(list[p]);
} else if(typeof list[p] === "object") { // this is not a reliable test!
flattenList(list[p], accumulator);
}
}
}
return accumulator;
}
This code makes a number of assumptions - we only have strings at the end of our objects etc. Alternatively, if you know the depth in advance, your current solution can be optimized by using concat :
var flattenedList = (function(list){
return Array.prototype.concat.apply([], list);
})([Constants.scope.namespaceA,Constants.scope.namespaceB]);
Here's an approach that allows for deeper nesting. I know that wasn't part of the goals, but I found it a more interesting problem. :-)
var flatten = (function() {
var toString = Object.prototype.toString, slice = Array.prototype.slice;
var flatten = function(input, output) {
var value;
output = (toString.call(output) == "[object Array]") ? output : [];
for (name in input) {if (input.hasOwnProperty(name)) {
value = input[name];
if (toString.call(value) == "[object Object]") {
flatten(value, output);
} else {
output.push(value);
}
}};
return output;
};
var merge = function(first, second) {
return first.concat(second);
}
return function() {
return slice.call(arguments).map(flatten).reduce(merge);
};
}());
This allows either approach:
flatten(Constants.scope);
flatten(Constants.scope.namespaceA, Constants.scope.namespaceN);
You can pass in as many separate arguments as you like, or one argument. They'll all be searched to arbitrary depths.
For some environments, you might have to shim Array.prototype functions map and reduce.
Assume I have an object:
var obj = {
foo:"bar",
fizz:"buzz"
};
I need to access a property of that object dynamically like so:
var objSetter = function(prop,val){
obj[prop] = val;
}
No problems there, except for that prop needs to be case insensitive in case the property name is passed into the function as, say, Foo instead of foo.
So how can I point to an object's property by name without regard to case? I would like to avoid iterating the entire object if possible.
Try this:
var myObject = { "mIxeDCaSEKeY": "value" };
var searchKey = 'mixedCaseKey';
var asLowercase = searchKey.toLowerCase();
myObject[Object.keys(myObject).find(key => key.toLowerCase() === asLowercase)];
You can alternatively already provide the searchKey in lowercase.
If you want it as a function:
/**
* #param {Object} object
* #param {string} key
* #return {any} value
*/
function getParameterCaseInsensitive(object, key) {
const asLowercase = key.toLowerCase();
return object[Object.keys(object)
.find(k => k.toLowerCase() === asLowercase)
];
}
If the key can't be found, then it'll return undefined, just like normal.
If you need to support older browsers, then you can use filter instead:
function getParameterCaseInsensitive(object, key) {
const asLowercase = key.toLowercase();
return object[Object.keys(object).filter(function(k) {
return k.toLowerCase() === asLowercase;
})[0]];
}
I suggest using the polyfills for Object.keys() and Array.filter() if you need even older support.
Note: If you want to also check non-enumerable keys, use Object.getOwnPropertyNames() instead of Object.keys().
Nerdy Note: This assumes your Object doesn't have a key undefined (eg: const foo = {[undefined]: 'bar'};). That's just weird.
Compare all the properties of obj with prop.
var objSetter = function(prop,val){
prop = (prop + "").toLowerCase();
for(var p in obj){
if(obj.hasOwnProperty(p) && prop == (p+ "").toLowerCase()){
obj[p] = val;
break;
}
}
}
For this, I prefer using the prototype over a standalone function just for ease of use and expressiveness. I just don't like funneling objects into functions if I don't have to.
Also, while the accepted answer works, I wanted a more comprehensive solution for both getting and setting that would behave as much like the native dot notation or bracket notation as possible.
With that in mind, I created a couple prototype functions for setting/getting an object property without regard to case. You have to remember to be VERY responsible when adding to the Object prototype. Especially when using JQuery and other libraries. Object.defineProperty() with enumerable set to false was used specifically to avoid conflict with JQuery. I also didn't bother naming the functions anything that indicates they are case-insensitive, but you certainly could. I like shorter names.
Here's the getter:
Object.defineProperty(Object.prototype, "getProp", {
value: function (prop) {
var key,self = this;
for (key in self) {
if (key.toLowerCase() == prop.toLowerCase()) {
return self[key];
}
}
},
//this keeps jquery happy
enumerable: false
});
Here's the setter:
Object.defineProperty(Object.prototype, "setProp", {
value: function (prop, val) {
var key,self = this;
var found = false;
if (Object.keys(self).length > 0) {
for (key in self) {
if (key.toLowerCase() == prop.toLowerCase()) {
//set existing property
found = true;
self[key] = val;
break;
}
}
}
if (!found) {
//if the property was not found, create it
self[prop] = val;
}
return val;
},
//this keeps jquery happy
enumerable: false
});
Now that we've created those functions, our code is super clean and concise and just works.
Case-insensitive getting:
var obj = {foo: 'bar', camelCase: 'humpy'}
obj.getProp("FOO"); //returns 'bar'
obj.getProp("fOO"); //returns 'bar'
obj.getProp("CAMELCASE"); //returns 'humpy'
obj.getProp("CamelCase"); //returns 'humpy'
Case-insensitive setting:
var obj = {foo: 'bar', camelCase: 'humpy'}
obj.setProp('CAmelCasE', 'super humpy'); //sets prop 'camelCase' to 'super humpy'
obj.setProp('newProp', 'newval'); //creates prop 'newProp' and sets val to 'newval'
obj.setProp('NewProp', 'anotherval'); //sets prop 'newProp' to 'anotherval'
Yet another variation on those already presented which pushes the iteration down into the Underscore/Lodash findKey function:
var _ = require('underscore');
var getProp = function (obj, name) {
var realName = _.findKey(obj, function (value, key) {
return key.toLowerCase() === name.toLowerCase();
});
return obj[realName];
};
For example:
var obj = { aa: 1, bB: 2, Cc: 3, DD: 4 };
getProp(obj, 'aa'); // 1
getProp(obj, 'AA'); // 1
getProp(obj, 'bb'); // 2
getProp(obj, 'BB'); // 2
getProp(obj, 'cc'); // 3
getProp(obj, 'CC'); // 3
getProp(obj, 'dd'); // 4
getProp(obj, 'DD'); // 4
getProp(obj, 'EE'); // undefined
This answer requires ES6.
const x = { 'aB': 1, 'X-Total-Count': 10, y3: 2 }
console.log(x[Object.keys(x).find(key=>{return key.match(/^ab$/i)})])
console.log(x[Object.keys(x).find(key=>{return key.match(/^x-total-count$/i)})])
console.log(x[Object.keys(x).find(key=>{return key.match(/^y3$/i)})])
It seems to me like a good candidate for Proxy with traps to convert string keys to either upper case or lower case and behaving like a regular object.
This works with either notation: dots or braquets
Here is the code:
'use strict';
function noCasePropObj(obj)
{
var handler =
{
get: function(target, key)
{
//console.log("key: " + key.toString());
if (typeof key == "string")
{
var uKey = key.toUpperCase();
if ((key != uKey) && (key in target))
return target[key];
return target[uKey];
}
return target[key];
},
set: function(target, key, value)
{
if (typeof key == "string")
{
var uKey = key.toUpperCase();
if ((key != uKey) && (key in target))
target[key] = value;
target[uKey] = value;
}
else
target[key] = value;
},
deleteProperty: function(target, key)
{
if (typeof key == "string")
{
var uKey = key.toUpperCase();
if ((key != uKey) && (key in target))
delete target[key];
if (uKey in target)
delete target[uKey];
}
else
delete target[key];
},
};
function checkAtomic(value)
{
if (typeof value == "object")
return new noCasePropObj(value); // recursive call only for Objects
return value;
}
var newObj;
if (typeof obj == "object")
{
newObj = new Proxy({}, handler);
// traverse the Original object converting string keys to upper case
for (var key in obj)
{
if (typeof key == "string")
{
var objKey = key.toUpperCase();
if (!(key in newObj))
newObj[objKey] = checkAtomic(obj[key]);
}
}
}
else if (Array.isArray(obj))
{
// in an array of objects convert to upper case string keys within each row
newObj = new Array();
for (var i = 0; i < obj.length; i++)
newObj[i] = checkAtomic(obj[i]);
}
return newObj; // object with upper cased keys
}
// Use Sample:
var b = {Name: "Enrique", last: "Alamo", AdDrEsS: {Street: "1233 Main Street", CITY: "Somewhere", zip: 33333}};
console.log("Original: " + JSON.stringify(b)); // Original: {"Name":"Enrique","last":"Alamo","AdDrEsS":{"Street":"1233 Main Street","CITY":"Somewhere","zip":33333}}
var t = noCasePropObj(b);
console.log(JSON.stringify(t)); // {"NAME":"Enrique","LAST":"Alamo","ADDRESS":{"STREET":"1233 Main Street","CITY":"Somewhere","ZIP":33333}}
console.log('.NaMe:' + t.NaMe); // .NaMe:Enrique
console.log('["naME"]:' + t["naME"]); // ["naME"]:Enrique
console.log('.ADDreSS["CitY"]:' + t.ADDreSS["CitY"]); // .ADDreSS["CitY"]:Somewhere
console.log('check:' + JSON.stringify(Object.getOwnPropertyNames(t))); // check:["NAME","LAST","ADDRESS"]
console.log('check2:' + JSON.stringify(Object.getOwnPropertyNames(t['AddresS']))); // check2:["STREET","CITY","ZIP"]
You could do this in order to "normalize" prop
var normalizedProp = prop.toLowerCase();
obj[normalizedProp] = val;
const getPropertyNoCase = (obj, prop) => obj[Object.keys(obj).find(key => key.toLowerCase() === prop.toLowerCase() )];
or
const getPropertyNoCase = (obj, prop) => {
const lowerProp = prop.toLowerCase(obj[Object.keys(obj).find(key => key.toLowerCase() === prop.toLowerCase() )];
}
The ES6 example posted by #nilloc is incorrect and will break in use.
Here is a working example:
const x = {'first':5,'X-Total-Count':10,'third':20};
console.log(x[Object.keys(x).reduce((result,key)=>{
if (!result) {
return key.match(/x-total-count/i)
} else {
return result;
}
},null)]);
or better yet, it should return undefined if the key doesn't exist:
const x = {'first':5,'X-Total-Count':10,'third':20};
console.log(x[Object.keys(x).reduce((result,key)=>{
if (!result) {
return key.match(/x-total-count/i) || undefined
} else {
return result;
}
},undefined)]);
One consideration is that the above example will return the last matching key in the object if there are multiple keys that match.
Here is an example with the code made into a function:
/**
* #param {Object} object
* #param {string} key
* #return {string||undefined} value || undefined
*/
function getKeyCase(obj,key) {
const re = new RegExp(key,"i");
return Object.keys(obj).reduce((result,key)=>{
if (!result) {
return key.match(re) || undefined
} else {
return result;
}
},undefined);
const x = {'first':5,'X-Total-Count':10,'third':20};
console.log(x[getKeyCase(x,"x-total-count")]);
Its really sad that the iteration can't be skipped as it seems. For me what is acceptable but may not be for everyone is to shape the object one time via iteration and then use it in regular hashmap fashion.
const hashmap = {
'FOO': 'foo as in function programming',
'bar': 'bar is in baz',
};
const shapedmap = Object.entries(hashmap).reduce(
(acc, [key, val]) => (acc[key.toUpperCase()] = val, acc), {}
);
for (const term of ['foo', 'bar', 'baz']) {
const match = shapedmap[term.toUpperCase()]
match && console.log('awesome, we got the term.', match);
};
Even if it just one time lookup has to be performed, it shouldn't less performant as any other iteration solution since after 1 pass, the lookup speed is constant. (I guess).
This is an old question, but it was the first one I found.
As #ZachSmith says, you can use a Proxy.
Here's some example code:
function lowercase(oldKey) {
// Check that it's a string.
return typeof oldKey === 'string' ? oldKey.toLowerCase() : oldKey;
}
const propertiesMap = new Map(
Object.keys(obj).map(propKey => [lowercase(propKey), obj[propKey]])
);
const caseInsensitiveGetHandler = {
get: function(target, property, receiver) {
return propertiesMap.get(lowercase(property));
}
};
obj = new Proxy(obj, caseInsensitiveGetHandler);
For my use case, I only needed to proxy the object's getter, but you may need to implement more of the Proxy methods.
There is no need for any iteration. Since prop might not be a string, it should be coerced to a string first where appropriate since that's what objects do natively. A simple getter function is:
function objGetter(prop) {
return obj[String(prop).toLowerCase()];
}
If there is a requirement is to restring access to own properties:
function objGetter(prop) {
prop = String(prop).toLowerCase();
if (obj.hasOwnProperty(prop)) {
return obj.prop;
}
}
and a setter:
function objSetter(prop, val) {
obj[String(prop).toLowerCase()] = val;
}
Heres a very simple code to do this
Assuming that data is the array of objects like
data=[{"A":"bc","B":"nn"}]
var data=data.reduce(function(prev, curr) {
var cc = curr; // current value
var K = Object.keys(cc); // get all keys
var n = {};
for (var i = 0; i < K.length; i++) {
var key = K[i];//get hte key
n[key.toLowerCase()] = cc[key] // convert to lowercase and assign
}
prev.push(n) // push to array
return prev;
}, [])
Output will be
data=[{"a":"bc","b":"nn"}]
You might only need to do case-insensitive matching (usually expensive because of object iteration) IF a case-sensitive match (cheap and quick) fails.
Say you have:
var your_object = { "Chicago" : 'hi' , "deTroiT" : 'word' , "atlanta" : 'get r dun' } ;
And you have, for whatever reason, the_value, Detroit:
if( your_object.hasOwnProperty( the_value ) )
{
// do what you need to do here
}
else
{ // since the case-sensitive match did not succeed,
// ... Now try a the more-expensive case-insensitive matching
for( let lvs_prop in your_object )
{ if( the_value.toLowerCase() == lvs_prop.toLowerCase() )
{
// do what you need to do here
break ;
} ;
}
} ;
why would we do it that complicated when we simply can make it all lower case:
var your_object = {
"chickago" : 'hi' ,
"detroit" : 'word',
"atlanta" : 'get r dun',
GetName: function (status) {
return this[status].name;
} };
to call it: your_object.GetName(your_var.toLowerCase());
Another simple way:
function getVal(obj, prop){
var val;
prop = (prop + "").toLowerCase();
for(var p in obj){
if(obj.hasOwnProperty(p) && prop == (p+ "").toLowerCase()){
val = obj[p]
break;
}
}
return val;
}
Use it like this:
var obj = {
foo:"bar",
fizz:"buzz"
};
getVal(obj,"FoO") -> returns "bar"
Here is a nice recursive function that allows you to traverse a javascript object in a case-insensitive way:
let testObject = {'a': {'B': {'cC': [1,2,3]}}}
let testSeq = ['a','b','cc']
function keySequence(o, kseq) {
if(kseq.length==0){ return o; }
let validKeys = Object.keys(o).filter(k=>k.toLowerCase()==kseq[0].toLowerCase());
if(validKeys.length==0) { return `Incorrect Key: ${kseq[0]}` }
return keySequence(o[validKeys[0]], kseq.slice(1))
}
keySequence(testObject, testSeq); //returns [1,2,3]
This will convert everything to lowercase, but in a bind this could help if you are not concerned with retaining case.
var somedata = {
"MixEdCase": 1234
}
var temp = JSON.parse(JSON.stringify(somedata).toLowerCase());
console.log(temp.mixedcase);
// or
console.log(temp["mixedcase"]);
So, you will need to get the object key that matches the case of the existing object, then use this to do your object update.
const obj = {
foo:"bar",
fizz:"buzz"
};
// to get obj.foo or obj.FOO or obj.foO returning "bar"
// create regex expression of case insensitive version of the key string
const regex=passedKey=> new RegExp(`^${passedKey}$`,'gi');
// find the key that matches the string you are passing
const formattedKey=passedKey=>Object.keys(obj).find(key=>regex(passedKey).test(key));
formattedKey('Foo'); // returns foo
formattedKey('FoO'); // returns foo
// consequently you can can use it like wise
obj[formattedKey('Foo')] // returns bar
obj[formattedKey('FoO')] // returns bar
obj[formattedKey('foo')] // returns bar