Default parameters in ES6

Question

The result of the function mentioned below is a little bit odd ! Someone can explain it, please. function test(a, b = 3, c = 42) {
return a + b + c;
}
console.log(test(5)); //50

Answer 1

It is right since 5 is passed to the first parameter a

Answer 2

Abhay! thank you for prompt reply. I am taken.

Answer 3

You can define the initial value of arguments while writing the function! You should have a clear explanation of this :))

Initial values work when no argument is passed in the function when you call them! Consider this :

function test(a = 5, b = 3, c = 42) {
return a + b + c;
}

console.log(test()); // 50

See, you didn’t pass any argument but still getting the output 50 because you defined the initial value of a, b & c. However, again consider this :

function test(a = 5, b = 3, c = 42) {
return a + b + c;
}

console.log(test(1, 2, 3)); // 6

This time you get 6 because you passed all three arguments of the function. And hence, the initial values don't work anymore :))

Now here is a quize for you. Tell me the answer without running the code :))

function test(a = 5, b, c = 5) {
return a + b + c;
}

console.log(test(5, 5, 5));

What will be the output?