Number of parameters

Question

Hi, if you declare 3 parameters when you name the function, can you then only use 2 or 1?

Answer 1

Yes, the remaining parameters will be set to undefined (which may cause errors depending on your function body).

https://www.sololearn.com/learn/JavaScript/1147/

You may also want to look into default parameters and variadic parameters (variadic functions) or the spread operator etc.

Answer 2

You can set default parameters, in case the user doesn't provide them to you,

function add(a = 0, b = 0) {
return a + b
}

add(5, 7) // 12
add() // 0

If i didn't set the default values for a and b in the function, and the user doesn't pass the values, they would become undefined, and it would return undefined + undefined which is equal to NaN (not a number)