JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://yandex.st/jquery/2.2.3/jquery.min.js"></script>
<div id="result" style="width: 500px;"></div>

JavaScript

// Available projections and corresponding eccentricity values.
var projections = [{
        name: 'wgs84Mercator',
        eccentricity: 0.0818191908426
    }, {
        name: 'sphericalMercator',
        eccentricity: 0
    }], 
    
    // To calculate the number of the required tile, you should set the parameters:
    // - map zoom level;
    // - geographic coordinates of the object falling within the tile;
    // - projection for which you need to get the tile.
    params = {
        z: 0,
        geoCoords: [55.733776, 37.587936],
        projection: projections[0]
   };
   
// Function for converting the geographic coordinates of an object
// into global pixel coordinates.
function fromGeoToPixels (lat, long, projection, z) {
    var x_p, y_p,
        pixelCoords,
        tilenumber = [],
        rho,
        pi = Math.PI,
        beta,   
        phi,
        theta,
        e = projection.eccentricity;
 
    rho = Math.pow(2, z + 8) / 2;
    beta = lat * pi / 180;
    phi = (1 - e * Math.sin(beta)) / (1 + e * Math.sin(beta));
    theta = Math.tan(pi / 4 + beta / 2) * Math.pow(phi, e / 2);
    
    x_p = rho * (1 + long / 180);
    y_p = rho * (1 - Math.log(theta) / pi);
    
    return [x_p, y_p];
}

// Function to calculate tile number based on global pixel coordinates.
function fromPixelsToTileNumber (x, y) {
    return [
        Math.floor(x / 256),
        Math.floor(y / 256)
    ];
}

// Convert the geographic coordinates of the object to global pixel coordinates.
pixelCoords = fromGeoToPixels(
    params.geoCoords[0],
    params.geoCoords[1],
    params.projection,
    params.z
);

// Calculate the tile number based on pixel coordinates.
tileNumber = fromPixelsToTileNumber(pixelCoords[0], pixelCoords[1]);

// Display the result.
document.addEventListener("DOMContentLoaded", function () {
    document.getElementById("result").innerHTML = "<b>Initial data:</b><p>" +
    "– zoom level: " + params.z + "<br/>" +
    "– geographic coordinates: [" +...