How to pass as two array as argument in a function?

Question

var arr1 = [1, 2, 3];
var arr2 = [4, 5];
function mover (arg1,arg2){
  return arg1 && arg2;
} 

My question: Am I doing it right? Because I expected in the answer [1, 2, 3] , [4, 5], and as you can see below, it only brings a response. And why does the console bring the answer twice? Another question, the array can only be inserted into the function once?

Console response:

console.log(mover(arr1,arr2));

[ 1, 2, 3 ]
[ 1, 2, 3 ]
=> undefined

Answer 1

Cannot return two values in a function. Each return that you give only returns one value. Thus, if you want to return more than one value for a function, you must use a fixed-size array. In addition, as suggested in the comments by @leofalmeida, it is also possible to use objects.

Returning two values using array:

For example, consider the function below. I want it to return the first parameter and the second parameter:

function twoValues(a, b) {
  // Note que estou retornando um array com os dois
  // valores que quero retornar.
  return [a, b];
}

console.log(twoValues('Luiz', 'Felipe'));

In your case, if you want to return two arrays:

function twoValues(a, b) {
  return [a, b];
}

console.log(twoValues([1, 2], [3, 4]));

Returning values using objects:

It is also possible to return an object. This approach is ideal if you want to return multiple values at the same time. An example would be:

function twoValuesViaObject(a, b) {
  return {
    first: a,
    second: b
    // ...
  }
}

console.log(twoValuesViaObject([1, 2], [3, 4]));

To learn more about the objects, read here.

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Operator &&

And in your case, the operator && does not work to return two values, since this is not even his function. In that case, he is making a short-circuit evaluation. To learn more about them, see that question.

As you can see, in your example:

var arr1 = [1, 2, 3];
var arr2 = [4, 5];

function mover(arg1,arg2) {
  return arg1 && arg2;
}

console.log(mover(arr1, arr2)); // [4, 5]

Only the arr2 is being returned, to the detriment of short-circuit evaluation. Basically, as the arr1 is a value Truthy, the second operand will be returned. To learn more, read the linked question above.

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Learn more...

For further information, I recommend reading about the allocation via structuring, that can help work with objects and arrays. ;)