Function Array and Parameter

can parameter be passed as an array inside a function? if so does that mean we can just use the () instead of [ array ]or do we do both ([array]) ?

Yes, arrays can be passed as a parameter inside a function.

function printer(data) {
    console.log(data);
}
printer([1, 2, 3, 4, 5]);

so you declare the array list outside of the function and use the param to hold the value of the array?

The array isn’t declared as such. We pass it to function, like passing any other type of value. In the above example, [1, 2, 3, 4, 5] will be stored in the data argument.

[1, 2, 3, 4, 5] could be stored in a variable too.

function printer(data) {
    console.log(data);
}
var someData = [1, 2, 3, 4, 5];
printer(someData);