The difference between php and node (2) -- function parameter reference

$a = [1,3];
function change_arr($arr) {
    $arr[0] = 200;
}
change_arr($a);
var_dump($a);

php prints the result as follows:

array(2) {
  [0]=>
  int(1)
  [1]=>
  int(3)
}

That is to say, php does not change the original actual parameters.
If you want to change, there are two ways,
the first is to change the function definition

$a = [1,3];
function change_arr(&$arr) { // only add a pass by reference here
    $arr[0] = 200;
}
change_arr($a);
var_dump($a);

Type 2: Use the return value

$a = [1,3];
function change_arr($arr) {
    $arr[0] = 200;
    return $arr;
}
$a = change_arr($a);
var_dump($a);

The above two ways of writing will lead to changes.
The result is as follows:

array(2) {
  [0]=>
  int(200)
  [1]=>
  int(3)
}

===================================================== =====================================================
_ ===================================

Start node here

var arr = [1,3];
function change_arr(arr2){
    arr2[0] = 200;
}

change_arr(arr);
arr.map((n)=>{
    console.log(n);
})

Good guy, modify the actual parameters directly.
Below is the print result

200
3

So node programming should be careful ~

previous link:
Difference between php and node (1) -- scope