String concatenation?

Question

JavaScript

for example, there is this. expression
let I = 'b'+'a'
is it possible to somehow refer to a and b? (except for working with a ready-made string i)
for example, by array index or something else
in a real example, these are strings of different content and length

Answer 1

.then - asynchronous operation

Answer 2

I don't know if I understood the question correctly:

var a= 'a', b= 'b';
b= b.toUpperCase();
var i= a+b;

Answer 3

no
PS. but you can save these 'a' and 'b' in separate variables before, concatenate them, but the original strings will remain in these variables

Answer 4

If I understand the question correctly, then something like this
const a = 'Mary';
const b = 'Hello';
console.log(`${a}, how are you? ${b}`);
console log(a+b);
console log(a);
console log(b);

Answer 5

I didn't understand the question. Where do these lines come from?
After the merging, it is no longer possible to divide back, since the Iinformation about the gluing boundary has been lost in the variable. But it is possible if this information is stored somewhere - for example, in the form of the length of at least one of the original strings.