JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container"></div>

JavaScript

var g = 7;
var C = [0.99999999999980993, 676.5203681218851, -1259.1392167224028, 771.32342877765313, -176.61502916214059, 12.507343278686905, -0.13857109526572012, 9.9843695780195716 * Math.pow(10, -6), 1.5056327351493116 * Math.pow(10, -7)];

function gamma(z) {

    if (z < 0.5) return Math.PI / (Math.sin(Math.PI * z) * gamma(1 - z));
    else {
        z -= 1;

        var x = C[0];
        for (var i = 1; i < g + 2; i++)
        x += C[i] / (z + i);

        var t = z + g + 0.5;
        return Math.sqrt(2 * Math.PI) * Math.pow(t, (z + 0.5)) * Math.exp(-t) * x;
    }
}

function init() {
    var c = document.getElementById('container');
    c.innerHTML = gamma(2.33);
}

init();