More Arguments

Spread syntax is a way of calling a JavaScript object with any number of arguments. So, you can make function like this:

const avg = (first = 0, ...others) {
    let sum = first;
    for (const value of others) { sum += value; }
    return sum / (1 + others.lenght);
 }

This can be called with any number of arguments. One thing to note is that if the argument is an array, the result will be NaN. But, you can call it by using the ... operator in front of the array. This will work:

let myArr = [1, 3, 5];
avg(...myArr);

javascript