let selected_user = '11';
const arrayOfUsers = ['11', '12', '13'];
console.log(arrayOfUsers); // ['11', '12', '13']
let indexMainUser = arrayOfUsers.indexOf(selected_user);
arrayOfUsers.splice(indexMainUser, 1);
console.log(arrayOfUsers); //  ['12', '13']

I have the above code in JavaScript and I am wondering why does a constant array gets modified with splice method?