Get first n elements of an array

Write a function that takes an array (a) as argument. Extract the first 3 elements of a. Return the resulting array
function
myFunction
(
a
)
{

return
}
Test Cases:
myFunction([1,2,3,4])
Expected
[1,2,3]
myFunction([5,4,3,2,1,0])
Expected
[5,4,3]
myFunction([99,1,1])
Expected
[99,1,1]