Mousewheel/Trackpad Zoom

Restrict wheel/trackpad zooming to integer zoom levels.

By default, the ol.interaction.MouseWheelZoom can leave the map at fractional zoom levels. If instead you want to constrain wheel/trackpad zooming to integer zoom levels, set constrainResolution: true when constructing the interaction.

<!DOCTYPE html>
<html>
  <head>
    <title>Mousewheel/Trackpad Zoom</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v4.6.4/css/ol.css" type="text/css">
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src=""></script>
    <script src="https://openlayers.org/en/v4.6.4/build/ol.js"></script>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script>
      var map = new ol.Map({
        interactions: ol.interaction.defaults({mouseWheelZoom: false}).extend([
          new ol.interaction.MouseWheelZoom({
            constrainResolution: true // force zooming to a integer zoom
          })
        ]),
        layers: [
          new ol.layer.Tile({
            source: new ol.source.OSM()
          })
        ],
        target: 'map',
        view: new ol.View({
          center: [0, 0],
          zoom: 2
        })
      });
    </script>
  </body>
</html>