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Now that we learned about objects and arrays,

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there's one common misconception I sometimes see in the Q & A section.

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Please check out that video I linked earlier in this article where I talk about primitive and reference

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types in Javascript because that is a crucial concept.

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Objects and arrays are so-called reference types and you'll learn all about that and what that is in

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the linked video

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so I'm not going to re-explain it here.

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They are reference types and therefore when I store an array in a constant hobbies, I can still edit

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this array without violating the restriction that the constants must not change,

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let me prove that to you. If I comment

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that out and I add a new line here and I use another method,

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the push method which allows me to add a new element to the existing array.

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So this will not return a new array,

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it will add it to the existing array

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and here, I will add programming.

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Now if I console log hobbies after pushing and I run node play.js, you'll see that's the output and we

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get no error about editing this constant.

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The reason for that is that reference types only store an address pointing at the place in memory where

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that array is stored and that pointer this address has not changed by us adding a new element,

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so the thing stored in this constant is just this pointer, just this address and this has not changed,

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therefore our constant value has not changed. The thing it's pointing at has changed

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but that totally does not matter here.

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And this is something you have to understand so that you don't wonder what's going on

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when we do edit in quotation marks a constant value.

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We're not really editing a thing that is stored in a constant,

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we're only editing the thing

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that constant thing is pointing at.