Remember to Set the Constructor Property when Changing the Prototype Passed or Don't?

JavaScript
1

I played with this concept a little, and I found out that on browser console, manually setting the prototype property to a new object doesn’t require you to reset the constructor property.

for fcc
for fcc700×422 20.6 KB

Duck.constructor === Bird is true both before and after setting Bird.prototype to new object

Is this only because of the difference between the FCC console and Browser Console or is there more to why this is?

2

Did you try the same in FCC, you will get the same output…

I believe the reason is this one (the order is important):

  • You create a Duck - I wouldn’t use Uppercase -
  • So a prototype is associated with Duck,
  • You reset Bird Prototype
  • To update Duck prototype, you have to call Duck = new Bird(…) again

I wrote a similar example on Node


 function Bird(){}
> undefined
 let Duck = new Bird
> undefined
 Bird.prototype = {}
> {}
 Duck.constructor == Bird
> true
 Duck = new Bird
> {}
 Duck.constructor == Bird
> false
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3

Thanks for the Pointing out the Uppercase, Its bad practice, I’ll try to avoid using it like that. But I don’t understand your explanation

4

The prototype isn’t updated unless you re-assign Duck = new Bird

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5

Do you mean Bird.prototype = { numLegs : 2} isn’t updated or trying to reset the prototype with Duck.prototype.constructor doesn’t work until I create a new instance of Bird? (I’m sorry if this question sounds silly, I really don’t understand)

6

Yes, exactly. You can try with numLegs, and it should be the same.

It’s not silly!

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7

:sweat_smile: :sweat_smile: Thanks Thanks I get it now

1 Like