Hello Carbide

pi.wc.js

// You can directly `require` any package from NPM, 
// and it'll automatically load the latest version
// and recursively satisfy all dependencies

var bigInt = require("big-integer");

// Code is automatically transpiled with Babel.JS
// so you can use all the ES6/7 features such as
// generators, async functions, fat arrow syntax,
// React JSX, destructuring and more
function* calculatePi(){
    let [q, r, t] = [1, 0, 1].map(x => bigInt(x)); // big
    let [k, n, l] = [1, 3, 3]

    while(true){
        if(q.times(4).plus(r).minus(t).lesser(t.times(n))){
            yield n
            let nr = r.minus(t.times(n)).times(10)
            n = +q.times(3).plus(r).times(10).divide(t).minus(n*10)
	        q = q.times(10)
            r = nr
        }else{
            n = +q.times(k*7).plus(2).plus(r.times(l)).divide(t.times(l))
            r = q.times(2).plus(r).times(l)
            q = q.times(k)
            t = t.times(l)
            l += 2
            k += 1
        }
    }
}

// It also automatically injects timing instrumentation
// in outer loops to populate a progress bar with an 
// estimate of the current computation progress
var it = calculatePi(), str = '';
for(var i = 0; i < 2000; i++){
    str += it.next().value;
}
str