How I built a clean Compound Interest Calculator in Vanilla JS

#webdev #programming #javascript #opensource

As indie hackers and developers, projecting our long-term investments and personal finance is just as important as writing code. I wanted a fast, ad-free tool for this, so I built a Compound Interest Calculator.

The Approach

I built this using 100% Vanilla JS. No server calls, no tracking scripts. Financial inputs are private and should stay strictly on the client side.

Here is a look at the core function implementing the compound interest formula:

function calculateCompoundInterest(principal, rate, years, compoundingFrequency) {
    const r = rate / 100;
    const n = compoundingFrequency;
    const t = years;

    const amount = principal * Math.pow((1 + (r / n)), (n * t));
    const interestEarned = amount - principal;

    return {
        totalAmount: amount.toFixed(2),
        totalInterest: interestEarned.toFixed(2)
    };
}