Write a function `createBankAccount(initialBalance)` that returns an object with `deposit(amount)`, `withdraw(amount)`, and `getBalance()`. Withdrawals should fail (return false) if insufficient funds.
Problem Statement
Examples
Input: const acc = createBankAccount(100); acc.deposit(50); acc.getBalance();
Output: 150
Explanation: Balance is safely maintained within the closure scope.
Complexity
Time Complexity: O(N)
Space Complexity: O(1)
Hints
Editorial & Approach
Problem Overview & Intuition
To solve Private Variables with Closures, we consider the execution characteristics of JavaScript engines. Write a function `createBankAccount(initialBalance)` that returns an object with `deposit(amount)`, `withdraw(amount)`, and `getBalance()`. Withdrawals should fail (return false) if insufficient funds. By utilizing idiomatic language constructs and clean algorithmic principles, we can accomplish this with optimal time and memory usage.
Step-by-Step Approach
- Understand Problem Contract: Identify input arguments, return type expectations, and edge cases (empty inputs, nullish values).
- Choose Core Mechanism: Use modern JavaScript patterns (use a closure to keep the balance private).
- Implement Logic: Handle state and transformations efficiently (withdraw should check if amount <= balance before deducting).
- Return Result: Ensure proper return format and preserve caller context if applicable.
Optimal Implementation (JavaScript)
function createBankAccount(initialBalance) {
let balance = initialBalance;
return {
deposit(amount) { balance += amount; return true; },
withdraw(amount) {
if (amount > balance) return false;
balance -= amount;
return true;
},
getBalance() { return balance; }
};
}Complexity Analysis
Edge Cases & Corner Traps Handled
- Empty or boundary inputs (empty arrays, strings, zero length).
- Type checks and unexpected values (e.g.
null,undefined, negative numbers). - Closure preservation and memory isolation between separate invocations.