Default values when destructuring an array in JavaScript

Variables can have default values. In this case, if the array element is absent for the variable, the default value will be taken. In the following example, the variable day defaults to 1:

javascriptlet arr = [2025, 12];
let [year, month, day = 1] = arr;

console.log(year);  // shows 2025
console.log(month); // shows 12
console.log(day);   // shows 1

But if there is a value in the array for the variable day, the default value will be ignored:

javascriptlet arr = [2025, 12, 31];
let [year, month, day = 1] = arr;

console.log(year);  // shows 2025
console.log(month); // shows 12
console.log(day);   // shows 31

javascriptlet arr = ['John', 'Smit', 'development', 'programmer'];

let name       = arr[0];
let surname    = arr[1];
let department = arr[2];

let position;
if (arr[3] !== undefined) {
  position = arr[3];
} else {
  position = 'trainee';
}