<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<link href="https://cdn.bootcss.com/openlayers/4.6.5/ol.css" rel="stylesheet">
<script src="https://cdn.bootcss.com/openlayers/4.6.5/ol.js"></script>
<style type="text/css">
#map {
position: absolute;
width: 100%;
height: 100%;
overflow: hidden;
left: 0;
top: 0;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<script>
var projection = ol.proj.get("EPSG:4326");
var projectionExtent = projection.getExtent();
var size = ol.extent.getWidth(projectionExtent) / 256;
var resolutions = [];
for (var z = 2; z < 19; ++z) {