Source from wi2l.de/sof.html
var x = -1;
var a = new Array(9);
var i = new Array(2);
x = x + 1;
a[x] = ["a", "b"];
x = x + 1;
a[x] = ["c", "d"];
i[0] = "e";
i[1] = "f";
x = x + 1;
a[x] = i;
i[0] = "g";
i[1] = "h";
x = x + 1;
a[x] = i;
console.log(a[1] + " " + a[2] + " " + a[3]);result is c,d g,h g,h but should be c,d e,f g,h.
i[0] = "e"; // these two lines
i[1] = "f";
x = x + 1;
a[x] = i;
i[0] = "g"; // are changing the same array as these two lines
i[1] = "h";
So when you add the array i in, and change it's value, it changes it everywhere you used that array. It doesn't make a copy or anything.
a[x] = [...i]a[2] seems to point to the memory address of i and not recover its value.
To counter this, you need to recover the value of i. You can do it this way:
a[x] = Object.values(i)
The code does what it is expected to do in the contents of array a is [["a","b"],["c","d"],i,i]
Because you change the value of i to [g,h] you change it in both places. If what you wanted to do was create a copy of the array you could change
x=x+1;
a[x]=i;
to:
i[0] = "e";
i[1] = "f";
x = x + 1;
a[x] = [...i]; //creates a new array with the contents of i
i[0] = "g";
i[1] = "h";
x = x + 1;
a[x] = i;
Doing this results in [["a","b"],["c","d"],["e","f"],i]
a[x] = [...i]