New array effect old array, even tho I copied it and not used the same refrence

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hey guys , got this weird bug,
I've created a new array from an existing array,
however when i update the objects in said copied array,
the objects in the original array are being updated as-well,
the reference shouldn't be the same so i have no idea why this is happening
the currentShape Array is an array containing 4 objects in total

the code:

JavaScript

function checkKey(e) {
  nextShape = [...currentShape];
  e.preventDefault();
  e = e || window.event;
  if (e.keyCode === 40) {
    direction = "down";
    nextShape.forEach(cell => cell.i++);

JavaScript

  drawShape();
}

drawShape is irrelevant since it already gets a modified array which isnt what its supposed to get,

What I have tried:

tried using slice,map to creat the new array, same effect

Posted 13-Feb-20 14:23pm

Member 14719507

Updated 14-Feb-20 2:59am

Richard Deeming

v2

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[no name] 13-Feb-20 20:42pm

"Copying" is not the same as "cloning". Copying creates references to existing objects. Cloning creates new objects with their own references.

Richard Deeming 14-Feb-20 8:46am

You've tagged this question as "Java", but your code appears to be "Javascript".

Despite the similar names, these are two completely separate languages.

3 solutions

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MadMyche · Answer 1 · 2020-02-13T14:42:00

Solution 1

What you are seeing is an example of Variable Assignment, which basically says that the 2 variables are equal.
What I think you want to do is to use the clone() method, which will make a new variable and duplicate the values from the old variable.

Reference:
Array Copy in Java[^]

Posted 13-Feb-20 14:42pm

MadMyche

CPallini · Answer 2 · 2020-02-13T21:26:00

Solution 2

Array Copy in Java[^].

Posted 13-Feb-20 21:26pm

CPallini

Patrice T · Answer 3 · 2020-02-14T03:00:00

Solution 3

Quote:
New array effect old array, even tho I copied it and not used the same refrence

Rule of thumb: in managed languages, anything that not a generic type (strings, arrays, objects) is copied by reference if you don't specify otherwise.

Posted 14-Feb-20 3:00am

Patrice T