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So as you can tell, maps in a way are pretty similar to objects, which of course raises the question, when

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should you use which?

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So let's compare the two. Maps can use any values and any types as keys, so you can have an object as

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a key, a string, a number and in the same map, you can have mixed key types. Objects on the other hand can

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have mixed key types but you are restricted to using strings, numbers or symbols,

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we'll learn about symbols later,

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so you have less flexibility there.

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You can't

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use a boolean as a key and an object,

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you can't use another object or an array. For large quantities of data

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and with that I mean more than 10 entries, really large quantities, maps can provide better performance

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than objects do. So that might be one possible use case

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if you're working with large amounts of key-value data which you need in your application and in many

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applications, you might never really have that much data but if you do have that, that might be a place

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where you want to use maps, whereas objects are perfect for small or medium sized sets of data.

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And with that, I really mean medium sized not in the sense of five key-value pairs but still pretty big,

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30, 40 key-value pairs,

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that's certainly not a problem for an object.

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Objects by the way will also have another advantage which we'll see once we dive deeper into objects

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in the objects

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deep dive module, you can have methods that interact with the data in the object,

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that's not really possible on maps.

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So if you have methods that need to do something with the data that's part of the object,

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that's a strong reason to use an object.

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Now maps also can yield better performance when adding and removing data frequently,

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so if you have some operation which adds key-value pairs and removes key-value pairs multiple times

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per second, then a map might be worth a look. Objects on the other hand in general are easier and quicker

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to create, not just because you have that shorter syntax with curly braces but also from a performance

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perspective, new map takes a bit longer than creating an object with curly braces,

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though as always, with all these performance things, it's always important to keep in mind that we're

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talking about differences which you won't feel in the majority of apps you're building.

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So in general, the summary I want to give you here, not just about maps versus objects but about arrays

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sets and maps and objects in general is that in probably around 98% of cases, you will work with

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arrays and objects. Sets and maps have their niche cases where they can shine for unique value which has

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to be unique in the case of sets, for large quantities of fast changing data

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in the case of maps or if you have some use case where you have some data, let's say an object, where

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you kind of want to attach extra data which you don't want to merge into the object, as we did it in

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this example I showed you in this module, then you could also think about using a map to use the object

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as a key and add the extra data as part of the map instead of as part of the object.

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But again in the vast majority of cases, you can focus on arrays and objects but since sets and maps

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exist and you might encounter them in other code and you might personally also end up in some application

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at some point of time where you can benefit from them,

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it's of course important to be aware of them and to know them. Well and with that, they're actually also

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are two specific versions of sets and maps which are also quite interesting.