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So we got started with generics and hopefully it's clear what types does here.

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We passed some extra information into the merge function so that we can work in a better way with the

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result of the merge function and that's typically what generics are therefore they allow you to continue

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working with your data in a typescript optimal way.

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Now in this case here however we would have a problem if I pass in let's say just a number 30 year of

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course typescript now frozen Arrow because it tried to access to h but accessing the name would work

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nonetheless if we save that it compiles without errors and if I print the overall merge object we see

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what I get back is just a hobby is a name in my object which makes sense because 30 is a number.

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And when we pass that as a second argument to object a sign which we in the end are doing here.

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Well then this just fails silently javascript doesn't throw an error it doesn't complain but of course

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it all doesn't merge 30 into the newly created object.

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You see there is no 30 in this object.

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Now how which javascript do so because 30 is not an object an object a sign only is capable of merging

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different objects with each other.

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So what we in the end want to say well we don't care about the exact type.

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We don't care about the exact structure of the object you're providing here for a new entity.

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But what we do care about is that both parameters both types t and you should be any kind of object

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but they should be an object at all times.

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And currently we're not saying that currently we're just saying this should be of any type I don't care.

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Now often that's not OK.

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You want to restrict the types of T and you hear some of your generic types and you can do that with

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type constraints for generic types.

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You can set certain constraints regarding the types your generic types can be based on and you do this

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with the extents keyword here in the angled brackets after the type which you want to constrain.

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So here we could say extends Object and with that I'm saying the T type can be any object with any structure

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but it has to be an object we can do the same for you.

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And if I do that you see now I already get an error here in the ITC and if I try to save that I also

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get an error in the compiler because the type 30 argument here is not a signal to type object.

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So that's of course the behavior we want here.

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Now we're forced to pass in an object again which is like this now we're forced to pass this in again

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and therefore we improve does function because now it really works and we no object assign ones to objects.

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So in the end we want to guarantee that we get two objects here by setting certain constraints on our

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generic types and these constraints here can be anything you can refer to object to string you could

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use your own type if you had it.

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You can also use union types here if you want to you're really flexible there.

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You can set any constraints you want.

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And of course you don't have to constrain all generic types if you just want to constrain you.

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You can do that in this example it just makes sense to constrain both because object design once two

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objects here but you're really flexible there.

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It is important to be aware of that concept of constraints though because that allows you to work with

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generic types and a better in an optimal way which is why it's unnecessary errors or strange behaviors

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as we had it before.