let counter = 0;        // counter = 0
counter = 5;            // counter = 5
counter += 3;           // counter = 8
counter++;              // counter = 9

let items = [];
items.push("Apple");     // items = ["Apple"]
items.push("Banana");    // items = ["Apple", "Banana"]
items.splice(0, 1);      // items = ["Banana"]