I’m learning about javascript using dynamic variables. I’ve got the following code and associated error which i didnt understand. I’ve read a lot of responses to similar javascript dynamic code but they don’t use eval(). (I’m using eval() in nodejs)

let updatedArray = { 
    "firstNameArray": 'haha',
    "lastNameArray": 'zaza',
    "count": 0
};

let name = { "batch": "1" }; 

let firstNames_1 = [];
let lastNames_1 = [];
let count_1 = 0;

eval( 'firstNames_' + name.batch ) = updatedArray.firstNameArray;
eval( 'lastNames_' + name.batch ) = updatedArray.lastNameArray;
eval( 'count_' + name.batch ) = updatedArray.count;

I’ve tried running the above code but i’m stuck at this nodejs error.

ReferenceError: Invalid left-hand side in assignment for eval( 'firstNames_' + name.batch ) = updatedArray.firstNameArray;