[SOLVED] Why are the outputs appeared different?

Question

If we access any length property of function in Javascript, it shows us the numbers of parameters in the function, right?

In my code, a function name getData1 where I use the (a, b, and ...rest) parameters, and a rest operator to collect parameters and in another function getData2 I assign a value to the parameters ( a, b=2, c). But why the output is different? Why length property doesn't show the exact numbers of the parameters? The output would be 3 for both, isn't it?

https://sololearn.com/compiler-playground/c1dVKxklFQHt/?ref=app

Answer 1

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/length

it does not include rest params and stops at the first param with default argument

Answer 2

right.

I feel arguments.length seems more useful,
but it is only available inside the function.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/arguments/length

Answer 3

Bob_Li That means after setting default value, the other parameters are not counted in second case, right?

Answer 4

Bob_Li Thanks for the clarification. That's what I think so.

Yes, this is only available inside the function and create a lot of anomalies!