Example on how to create permalinks.
In this example the HTML 5 History API is used to update the browser URL with the current zoom-level, center and rotation when the map is moved. Note that the History API is not supported in all browsers, one might consider to use a a polyfill.
import 'ol/ol.css';
import Map from 'ol/Map';
import OSM from 'ol/source/OSM';
import TileLayer from 'ol/layer/Tile';
import View from 'ol/View';
// default zoom, center and rotation
let zoom = 2;
let center = [0, 0];
let rotation = 0;
if (window.location.hash !== '') {
// try to restore center, zoom-level and rotation from the URL
const hash = window.location.hash.replace('#map=', '');
const parts = hash.split('/');
if (parts.length === 4) {
zoom = parseFloat(parts[0]);
center = [parseFloat(parts[1]), parseFloat(parts[2])];
rotation = parseFloat(parts[3]);
}
}
const map = new Map({
layers: [
new TileLayer({
source: new OSM(),
}),
],
target: 'map',
view: new View({
center: center,
zoom: zoom,
rotation: rotation,
}),
});
let shouldUpdate = true;
const view = map.getView();
const updatePermalink = function () {
if (!shouldUpdate) {
// do not update the URL when the view was changed in the 'popstate' handler
shouldUpdate = true;
return;
}
const center = view.getCenter();
const hash =
'#map=' +
view.getZoom().toFixed(2) +
'/' +
center[0].toFixed(2) +
'/' +
center[1].toFixed(2) +
'/' +
view.getRotation();
const state = {
zoom: view.getZoom(),
center: view.getCenter(),
rotation: view.getRotation(),
};
window.history.pushState(state, 'map', hash);
};
map.on('moveend', updatePermalink);
// restore the view state when navigating through the history, see
// https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onpopstate
window.addEventListener('popstate', function (event) {
if (event.state === null) {
return;
}
map.getView().setCenter(event.state.center);
map.getView().setZoom(event.state.zoom);
map.getView().setRotation(event.state.rotation);
shouldUpdate = false;
});
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Permalink</title>
<!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
<script src="https://unpkg.com/elm-pep"></script>
<!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
<script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,URL,TextDecoder,Number.isInteger"></script>
<style>
.map {
width: 100%;
height:400px;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<script src="main.js"></script>
</body>
</html>
{
"name": "permalink",
"dependencies": {
"ol": "6.6.1"
},
"devDependencies": {
"parcel": "^2.0.0-beta.1"
},
"scripts": {
"start": "parcel index.html",
"build": "parcel build --public-url . index.html"
}
}