114. Counter Function with Closure

Implement counter - create an independent counter object backed by closure state.

Requirements

1) Input

• Accept an optional initial number initialValue.
• If omitted, default to 0.

2) Output API

• Return an object with two methods:
• increment(): increase by 1 and return the new value.
• decrement(): decrease by 1 and return the new value.

3) State model

• Each counter instance must keep independent state.
• Methods should rely on closed-over state (not shared/global state).

Examples

const c = counter(0)
c.increment() // 1
c.increment() // 2
c.decrement() // 1

const a = counter(10)
const b = counter(5)
a.increment() // 11
b.decrement() // 4