Edit

Moveend Event


Use of the moveend event.

In this example, a listener is registered for the map's moveend event. Whenever this listener is called, it updates the inputs below with the map extent in decimal degrees.

Copy 
index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Moveend Event</title>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <label>top</label><input type="text" id="top">
    <label>right</label><input type="text" id="right"><br>
    <label>bottom</label><input type="text" id="bottom">
    <label>left</label><input type="text" id="left">
    <script src="index.js"></script>
  </body>
</html>
Copy 
index.jsimport 'ol/ol.css';
import Map from 'ol/Map';
import View from 'ol/View';
import {getBottomLeft, getTopRight} from 'ol/extent';
import TileLayer from 'ol/layer/Tile';
import {toLonLat} from 'ol/proj';
import OSM from 'ol/source/OSM';


var map = new Map({
  layers: [
    new TileLayer({
      source: new OSM()
    })
  ],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2
  })
});

function display(id, value) {
  document.getElementById(id).value = value.toFixed(2);
}

function wrapLon(value) {
  var worlds = Math.floor((value + 180) / 360);
  return value - (worlds * 360);
}

function onMoveEnd(evt) {
  var map = evt.map;
  var extent = map.getView().calculateExtent(map.getSize());
  var bottomLeft = toLonLat(getBottomLeft(extent));
  var topRight = toLonLat(getTopRight(extent));
  display('left', wrapLon(bottomLeft[0]));
  display('bottom', bottomLeft[1]);
  display('right', wrapLon(topRight[0]));
  display('top', topRight[1]);
}

map.on('moveend', onMoveEnd);
Copy 
package.json{
  "name": "moveend",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}