How to destructure an object to an already defined variable? [duplicate]

Answer 1

You need to use assignment without declaration syntax:

({
    screenings,
    size
} = source);

Babel REPL Example

From the linked docs:

The ( .. ) around the assignment statement is required syntax when using object literal destructuring assignment without a declaration

And obviously you need to use this as you can't redeclare a let variable. If you were using var, you could just redeclare var { screenings, size } = source;