Web Worker Calculates Pi JavaScript

Webworker-calculatepi.js

function calculatePi() {
    var result = 0;
    var denominator = 1;
    var add = true;
    while (true) {
        if(add) {
            result = result + 4/denominator;
            add = false;
        } else {
            result = result - 4/denominator;
            add = true;
        }
        this.postMessage(result);
        denominator = denominator + 2;
    }
}

calculatePi();