how to change the array into variable in node.js code example

Example 1: modify array js

let newArray = oldArray.map(funcToEachElem);

Example 2: how to modify an array

let schedule = ['I', 'have', 'a', 'meeting', 'with'];
// adds 3 new elements to the array
schedule.splice(5, 0, 'some', 'clients', 'tommorrow');
console.log(schedule); 
// ["I", "have", "a", "meeting", "with", "some", "clients", "tommorrow"]