diff --git a/examples/canvas-gradient-pattern.js b/examples/canvas-gradient-pattern.js
index e38ee0e43e..d5a6cd25e3 100644
--- a/examples/canvas-gradient-pattern.js
+++ b/examples/canvas-gradient-pattern.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getWidth} from '../src/ol/extent.js';
 import GeoJSON from '../src/ol/format/GeoJSON.js';
 import {DEVICE_PIXEL_RATIO} from '../src/ol/has.js';
 import VectorLayer from '../src/ol/layer/Vector.js';
@@ -25,7 +25,7 @@ function gradient(feature, resolution) {
   // we just divide the geometry's extent width by resolution and multiply with
   // pixelRatio to match the renderer's pixel coordinate system.
   const grad = context.createLinearGradient(0, 0,
-    _ol_extent_.getWidth(extent) / resolution * pixelRatio, 0);
+    getWidth(extent) / resolution * pixelRatio, 0);
   grad.addColorStop(0, 'red');
   grad.addColorStop(1 / 6, 'orange');
   grad.addColorStop(2 / 6, 'yellow');
diff --git a/examples/earthquake-clusters.js b/examples/earthquake-clusters.js
index 2530e0afe9..e9ff625c94 100644
--- a/examples/earthquake-clusters.js
+++ b/examples/earthquake-clusters.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {createEmpty, getWidth, getHeight, extend} from '../src/ol/extent.js';
 import KML from '../src/ol/format/KML.js';
 import {defaults as defaultInteractions} from '../src/ol/interaction.js';
 import Select from '../src/ol/interaction/Select.js';
@@ -65,13 +65,13 @@ const calculateClusterInfo = function(resolution) {
   for (let i = features.length - 1; i >= 0; --i) {
     feature = features[i];
     const originalFeatures = feature.get('features');
-    const extent = _ol_extent_.createEmpty();
+    const extent = createEmpty();
     let j, jj;
     for (j = 0, jj = originalFeatures.length; j < jj; ++j) {
-      _ol_extent_.extend(extent, originalFeatures[j].getGeometry().getExtent());
+      extend(extent, originalFeatures[j].getGeometry().getExtent());
     }
     maxFeatureCount = Math.max(maxFeatureCount, jj);
-    radius = 0.25 * (_ol_extent_.getWidth(extent) + _ol_extent_.getHeight(extent)) /
+    radius = 0.25 * (getWidth(extent) + getHeight(extent)) /
         resolution;
     feature.set('radius', radius);
   }
diff --git a/examples/moveend.js b/examples/moveend.js
index 1e304d2f62..73fa95b1b7 100644
--- a/examples/moveend.js
+++ b/examples/moveend.js
@@ -1,7 +1,7 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
 import {defaults as defaultControls} from '../src/ol/control.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getBottomLeft, getTopRight} from '../src/ol/extent.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {toLonLat} from '../src/ol/proj.js';
 import OSM from '../src/ol/source/OSM.js';
@@ -37,8 +37,8 @@ function wrapLon(value) {
 function onMoveEnd(evt) {
   const map = evt.map;
   const extent = map.getView().calculateExtent(map.getSize());
-  const bottomLeft = toLonLat(_ol_extent_.getBottomLeft(extent));
-  const topRight = toLonLat(_ol_extent_.getTopRight(extent));
+  const bottomLeft = toLonLat(getBottomLeft(extent));
+  const topRight = toLonLat(getTopRight(extent));
   display('left', wrapLon(bottomLeft[0]));
   display('bottom', bottomLeft[1]);
   display('right', wrapLon(topRight[0]));
diff --git a/examples/reprojection-by-code.js b/examples/reprojection-by-code.js
index 47a202febf..346cb3067a 100644
--- a/examples/reprojection-by-code.js
+++ b/examples/reprojection-by-code.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {applyTransform} from '../src/ol/extent.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {get as getProjection, getTransform} from '../src/ol/proj.js';
 import {register} from '../src/ol/proj/proj4.js';
@@ -49,7 +49,7 @@ function setProjection(code, name, proj4def, bbox) {
   const fromLonLat = getTransform('EPSG:4326', newProj);
 
   // very approximate calculation of projection extent
-  const extent = _ol_extent_.applyTransform(
+  const extent = applyTransform(
     [bbox[1], bbox[2], bbox[3], bbox[0]], fromLonLat);
   newProj.setExtent(extent);
   const newView = new View({
diff --git a/examples/reprojection.js b/examples/reprojection.js
index b33873f8a1..ca57e6e115 100644
--- a/examples/reprojection.js
+++ b/examples/reprojection.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getWidth, getCenter} from '../src/ol/extent.js';
 import WMTSCapabilities from '../src/ol/format/WMTSCapabilities.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {get as getProjection} from '../src/ol/proj.js';
@@ -128,7 +128,7 @@ layers['grandcanyon'] = new TileLayer({
 });
 
 const startResolution =
-    _ol_extent_.getWidth(getProjection('EPSG:3857').getExtent()) / 256;
+    getWidth(getProjection('EPSG:3857').getExtent()) / 256;
 const resolutions = new Array(22);
 for (let i = 0, ii = resolutions.length; i < ii; ++i) {
   resolutions[i] = startResolution / Math.pow(2, i);
@@ -175,7 +175,7 @@ function updateViewProjection() {
   const newProjExtent = newProj.getExtent();
   const newView = new View({
     projection: newProj,
-    center: _ol_extent_.getCenter(newProjExtent || [0, 0, 0, 0]),
+    center: getCenter(newProjExtent || [0, 0, 0, 0]),
     zoom: 0,
     extent: newProjExtent || undefined
   });
diff --git a/examples/static-image.js b/examples/static-image.js
index 3566e6f416..5c937e7e97 100644
--- a/examples/static-image.js
+++ b/examples/static-image.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getCenter} from '../src/ol/extent.js';
 import ImageLayer from '../src/ol/layer/Image.js';
 import Projection from '../src/ol/proj/Projection.js';
 import Static from '../src/ol/source/ImageStatic.js';
@@ -30,7 +30,7 @@ const map = new Map({
   target: 'map',
   view: new View({
     projection: projection,
-    center: _ol_extent_.getCenter(extent),
+    center: getCenter(extent),
     zoom: 2,
     maxZoom: 8
   })
diff --git a/examples/street-labels.js b/examples/street-labels.js
index ab8f875176..8d21993ab1 100644
--- a/examples/street-labels.js
+++ b/examples/street-labels.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getCenter} from '../src/ol/extent.js';
 import GeoJSON from '../src/ol/format/GeoJSON.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import VectorLayer from '../src/ol/layer/Vector.js';
@@ -41,7 +41,7 @@ const map = new Map({
   target: 'map',
   view: new View({
     extent: viewExtent,
-    center: _ol_extent_.getCenter(viewExtent),
+    center: getCenter(viewExtent),
     zoom: 17,
     minZoom: 14
   })
diff --git a/examples/vector-label-decluttering.js b/examples/vector-label-decluttering.js
index a7c7c6bb34..cb340acbdf 100644
--- a/examples/vector-label-decluttering.js
+++ b/examples/vector-label-decluttering.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getWidth} from '../src/ol/extent.js';
 import GeoJSON from '../src/ol/format/GeoJSON.js';
 import VectorLayer from '../src/ol/layer/Vector.js';
 import VectorSource from '../src/ol/source/Vector.js';
@@ -26,7 +26,7 @@ const labelStyle = new Style({
       let widest = 0;
       for (let i = 0, ii = polygons.length; i < ii; ++i) {
         const polygon = polygons[i];
-        const width = _ol_extent_.getWidth(polygon.getExtent());
+        const width = getWidth(polygon.getExtent());
         if (width > widest) {
           widest = width;
           geometry = polygon;
diff --git a/examples/wms-custom-tilegrid-512x256.js b/examples/wms-custom-tilegrid-512x256.js
index db334e5987..cdffd2d696 100644
--- a/examples/wms-custom-tilegrid-512x256.js
+++ b/examples/wms-custom-tilegrid-512x256.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getWidth} from '../src/ol/extent.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {get as getProjection} from '../src/ol/proj.js';
 import OSM from '../src/ol/source/OSM.js';
@@ -9,7 +9,7 @@ import TileGrid from '../src/ol/tilegrid/TileGrid.js';
 
 
 const projExtent = getProjection('EPSG:3857').getExtent();
-const startResolution = _ol_extent_.getWidth(projExtent) / 256;
+const startResolution = getWidth(projExtent) / 256;
 const resolutions = new Array(22);
 for (let i = 0, ii = resolutions.length; i < ii; ++i) {
   resolutions[i] = startResolution / Math.pow(2, i);
diff --git a/examples/wms-time.js b/examples/wms-time.js
index c68aa1ba73..7f65044055 100644
--- a/examples/wms-time.js
+++ b/examples/wms-time.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getCenter} from '../src/ol/extent.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {transformExtent} from '../src/ol/proj.js';
 import Stamen from '../src/ol/source/Stamen.js';
@@ -34,7 +34,7 @@ const map = new Map({
   layers: layers,
   target: 'map',
   view: new View({
-    center: _ol_extent_.getCenter(extent),
+    center: getCenter(extent),
     zoom: 4
   })
 });
diff --git a/examples/wmts-dimensions.js b/examples/wmts-dimensions.js
index df31a6a486..2c9504680d 100644
--- a/examples/wmts-dimensions.js
+++ b/examples/wmts-dimensions.js
@@ -1,6 +1,6 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getWidth, getTopLeft} from '../src/ol/extent.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {get as getProjection} from '../src/ol/proj.js';
 import OSM from '../src/ol/source/OSM.js';
@@ -11,7 +11,7 @@ import WMTSTileGrid from '../src/ol/tilegrid/WMTS.js';
 // create the WMTS tile grid in the google projection
 const projection = getProjection('EPSG:3857');
 const tileSizePixels = 256;
-const tileSizeMtrs = _ol_extent_.getWidth(projection.getExtent()) / tileSizePixels;
+const tileSizeMtrs = getWidth(projection.getExtent()) / tileSizePixels;
 const matrixIds = [];
 const resolutions = [];
 for (let i = 0; i <= 14; i++) {
@@ -19,7 +19,7 @@ for (let i = 0; i <= 14; i++) {
   resolutions[i] = tileSizeMtrs / Math.pow(2, i);
 }
 const tileGrid = new WMTSTileGrid({
-  origin: _ol_extent_.getTopLeft(projection.getExtent()),
+  origin: getTopLeft(projection.getExtent()),
   resolutions: resolutions,
   matrixIds: matrixIds
 });
diff --git a/examples/wmts-ign.js b/examples/wmts-ign.js
index 2967e7e27e..0b4562e866 100644
--- a/examples/wmts-ign.js
+++ b/examples/wmts-ign.js
@@ -1,7 +1,7 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
 import {defaults as defaultControls} from '../src/ol/control.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getWidth} from '../src/ol/extent.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {fromLonLat, get as getProjection} from '../src/ol/proj.js';
 import WMTS from '../src/ol/source/WMTS.js';
@@ -24,7 +24,7 @@ const map = new Map({
 const resolutions = [];
 const matrixIds = [];
 const proj3857 = getProjection('EPSG:3857');
-const maxResolution = _ol_extent_.getWidth(proj3857.getExtent()) / 256;
+const maxResolution = getWidth(proj3857.getExtent()) / 256;
 
 for (let i = 0; i < 18; i++) {
   matrixIds[i] = i.toString();
diff --git a/examples/wmts.js b/examples/wmts.js
index 1c017ee50b..8eadd4555b 100644
--- a/examples/wmts.js
+++ b/examples/wmts.js
@@ -1,7 +1,7 @@
 import Map from '../src/ol/Map.js';
 import View from '../src/ol/View.js';
 import {defaults as defaultControls} from '../src/ol/control.js';
-import * as _ol_extent_ from '../src/ol/extent.js';
+import {getWidth, getTopLeft} from '../src/ol/extent.js';
 import TileLayer from '../src/ol/layer/Tile.js';
 import {get as getProjection} from '../src/ol/proj.js';
 import OSM from '../src/ol/source/OSM.js';
@@ -11,7 +11,7 @@ import WMTSTileGrid from '../src/ol/tilegrid/WMTS.js';
 
 const projection = getProjection('EPSG:3857');
 const projectionExtent = projection.getExtent();
-const size = _ol_extent_.getWidth(projectionExtent) / 256;
+const size = getWidth(projectionExtent) / 256;
 const resolutions = new Array(14);
 const matrixIds = new Array(14);
 for (let z = 0; z < 14; ++z) {
@@ -38,7 +38,7 @@ const map = new Map({
         format: 'image/png',
         projection: projection,
         tileGrid: new WMTSTileGrid({
-          origin: _ol_extent_.getTopLeft(projectionExtent),
+          origin: getTopLeft(projectionExtent),
           resolutions: resolutions,
           matrixIds: matrixIds
         }),
diff --git a/test/rendering/ol/layer/tile.test.js b/test/rendering/ol/layer/tile.test.js
index 82b90c2375..9f93c67092 100644
--- a/test/rendering/ol/layer/tile.test.js
+++ b/test/rendering/ol/layer/tile.test.js
@@ -1,6 +1,6 @@
 import Map from '../../../../src/ol/Map.js';
 import View from '../../../../src/ol/View.js';
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {getSize} from '../../../../src/ol/extent.js';
 import Point from '../../../../src/ol/geom/Point.js';
 import TileLayer from '../../../../src/ol/layer/Tile.js';
 import {assign} from '../../../../src/ol/obj.js';
@@ -146,8 +146,8 @@ describe('ol.rendering.layer.Tile', function() {
 
     function centerExtent(map) {
       const c = map.getView().calculateExtent(map.getSize());
-      const qw = _ol_extent_.getSize(c)[0] / 4;
-      const qh = _ol_extent_.getSize(c)[1] / 4;
+      const qw = getSize(c)[0] / 4;
+      const qh = getSize(c)[1] / 4;
       return [c[0] + qw, c[1] + qh, c[2] - qw, c[3] - qh];
     }
 
diff --git a/test/spec/ol/format/esrijson.test.js b/test/spec/ol/format/esrijson.test.js
index f09ad847ef..4f92375755 100644
--- a/test/spec/ol/format/esrijson.test.js
+++ b/test/spec/ol/format/esrijson.test.js
@@ -1,5 +1,5 @@
 import Feature from '../../../../src/ol/Feature.js';
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {equals} from '../../../../src/ol/extent.js';
 import EsriJSON from '../../../../src/ol/format/EsriJSON.js';
 import LineString from '../../../../src/ol/geom/LineString.js';
 import LinearRing from '../../../../src/ol/geom/LinearRing.js';
@@ -305,7 +305,7 @@ describe('ol.format.EsriJSON', function() {
         expect(first.getId()).to.be(6406);
         const firstGeom = first.getGeometry();
         expect(firstGeom).to.be.a(Polygon);
-        expect(_ol_extent_.equals(firstGeom.getExtent(), [
+        expect(equals(firstGeom.getExtent(), [
           -10585772.743554419, 4712365.161160459,
           -10579560.16462974, 4716567.373073828
         ])).to.be(true);
@@ -316,7 +316,7 @@ describe('ol.format.EsriJSON', function() {
         expect(last.getId()).to.be(6030);
         const lastGeom = last.getGeometry();
         expect(lastGeom).to.be.a(Polygon);
-        expect(_ol_extent_.equals(lastGeom.getExtent(), [
+        expect(equals(lastGeom.getExtent(), [
           -10555714.026858449, 4576511.565880965,
           -10553671.199322715, 4578554.9934867555
         ])).to.be(true);
diff --git a/test/spec/ol/format/geojson.test.js b/test/spec/ol/format/geojson.test.js
index 07b48e7546..1ebb8faf26 100644
--- a/test/spec/ol/format/geojson.test.js
+++ b/test/spec/ol/format/geojson.test.js
@@ -1,5 +1,5 @@
 import Feature from '../../../../src/ol/Feature.js';
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {equals} from '../../../../src/ol/extent.js';
 import GeoJSON from '../../../../src/ol/format/GeoJSON.js';
 import Circle from '../../../../src/ol/geom/Circle.js';
 import GeometryCollection from '../../../../src/ol/geom/GeometryCollection.js';
@@ -302,7 +302,7 @@ describe('ol.format.GeoJSON', function() {
         expect(first.getId()).to.be('AFG');
         const firstGeom = first.getGeometry();
         expect(firstGeom).to.be.a(Polygon);
-        expect(_ol_extent_.equals(firstGeom.getExtent(),
+        expect(equals(firstGeom.getExtent(),
           [60.52843, 29.318572, 75.158028, 38.486282]))
           .to.be(true);
 
@@ -312,7 +312,7 @@ describe('ol.format.GeoJSON', function() {
         expect(last.getId()).to.be('ZWE');
         const lastGeom = last.getGeometry();
         expect(lastGeom).to.be.a(Polygon);
-        expect(_ol_extent_.equals(lastGeom.getExtent(),
+        expect(equals(lastGeom.getExtent(),
           [25.264226, -22.271612, 32.849861, -15.507787]))
           .to.be(true);
         done();
diff --git a/test/spec/ol/format/mvt.test.js b/test/spec/ol/format/mvt.test.js
index 34607ebde7..a1eefdd8ed 100644
--- a/test/spec/ol/format/mvt.test.js
+++ b/test/spec/ol/format/mvt.test.js
@@ -1,5 +1,5 @@
 import Feature from '../../../../src/ol/Feature.js';
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {getWidth} from '../../../../src/ol/extent.js';
 import MVT from '../../../../src/ol/format/MVT.js';
 import Point from '../../../../src/ol/geom/Point.js';
 import Polygon from '../../../../src/ol/geom/Polygon.js';
@@ -78,7 +78,7 @@ where('ArrayBuffer.isView').describe('ol.format.MVT', function() {
       const format = new MVT();
       format.readFeatures(data);
       const extent = format.getLastExtent();
-      expect(_ol_extent_.getWidth(extent)).to.be(4096);
+      expect(getWidth(extent)).to.be(4096);
     });
 
   });
diff --git a/test/spec/ol/geom/linestring.test.js b/test/spec/ol/geom/linestring.test.js
index b8975822a0..1646df628e 100644
--- a/test/spec/ol/geom/linestring.test.js
+++ b/test/spec/ol/geom/linestring.test.js
@@ -1,4 +1,4 @@
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {isEmpty} from '../../../../src/ol/extent.js';
 import LineString from '../../../../src/ol/geom/LineString.js';
 
 
@@ -26,7 +26,7 @@ describe('ol.geom.LineString', function() {
     });
 
     it('has an empty extent', function() {
-      expect(_ol_extent_.isEmpty(lineString.getExtent())).to.be(true);
+      expect(isEmpty(lineString.getExtent())).to.be(true);
     });
 
     it('has empty flat coordinates', function() {
diff --git a/test/spec/ol/geom/multilinestring.test.js b/test/spec/ol/geom/multilinestring.test.js
index 461cab961b..ba6b7d67d9 100644
--- a/test/spec/ol/geom/multilinestring.test.js
+++ b/test/spec/ol/geom/multilinestring.test.js
@@ -1,4 +1,4 @@
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {isEmpty} from '../../../../src/ol/extent.js';
 import LineString from '../../../../src/ol/geom/LineString.js';
 import MultiLineString from '../../../../src/ol/geom/MultiLineString.js';
 
@@ -27,7 +27,7 @@ describe('ol.geom.MultiLineString', function() {
     });
 
     it('has an empty extent', function() {
-      expect(_ol_extent_.isEmpty(multiLineString.getExtent())).to.be(true);
+      expect(isEmpty(multiLineString.getExtent())).to.be(true);
     });
 
     it('has empty flat coordinates', function() {
diff --git a/test/spec/ol/geom/multipoint.test.js b/test/spec/ol/geom/multipoint.test.js
index d5a3b39ff0..308f7c3ac9 100644
--- a/test/spec/ol/geom/multipoint.test.js
+++ b/test/spec/ol/geom/multipoint.test.js
@@ -1,4 +1,4 @@
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {isEmpty} from '../../../../src/ol/extent.js';
 import MultiPoint from '../../../../src/ol/geom/MultiPoint.js';
 import Point from '../../../../src/ol/geom/Point.js';
 
@@ -27,7 +27,7 @@ describe('ol.geom.MultiPoint', function() {
     });
 
     it('has an empty extent', function() {
-      expect(_ol_extent_.isEmpty(multiPoint.getExtent())).to.be(true);
+      expect(isEmpty(multiPoint.getExtent())).to.be(true);
     });
 
     it('has empty flat coordinates', function() {
diff --git a/test/spec/ol/geom/polygon.test.js b/test/spec/ol/geom/polygon.test.js
index 44018b0b85..03c1b24c96 100644
--- a/test/spec/ol/geom/polygon.test.js
+++ b/test/spec/ol/geom/polygon.test.js
@@ -1,4 +1,4 @@
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {isEmpty, boundingExtent} from '../../../../src/ol/extent.js';
 import Circle from '../../../../src/ol/geom/Circle.js';
 import LinearRing from '../../../../src/ol/geom/LinearRing.js';
 import Polygon, {fromCircle, fromExtent} from '../../../../src/ol/geom/Polygon.js';
@@ -28,7 +28,7 @@ describe('ol/geom/Polygon', function() {
     });
 
     it('has an empty extent', function() {
-      expect(_ol_extent_.isEmpty(polygon.getExtent())).to.be(true);
+      expect(isEmpty(polygon.getExtent())).to.be(true);
     });
 
     it('has empty flat coordinates', function() {
@@ -221,25 +221,25 @@ describe('ol/geom/Polygon', function() {
 
       it('does not intersect outside extent', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([outsideOuter]))).to.be(false);
+          boundingExtent([outsideOuter]))).to.be(false);
       });
 
       it('does intersect inside extent', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([inside]))).to.be(true);
+          boundingExtent([inside]))).to.be(true);
       });
 
       it('does intersect boundary extent', function() {
         const firstMidX = (outerRing[0][0] + outerRing[1][0]) / 2;
         const firstMidY = (outerRing[0][1] + outerRing[1][1]) / 2;
 
-        expect(polygon.intersectsExtent(_ol_extent_.boundingExtent([[firstMidX,
+        expect(polygon.intersectsExtent(boundingExtent([[firstMidX,
           firstMidY]]))).to.be(true);
       });
 
       it('does not intersect extent fully contained by inner ring', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([insideInner]))).to.be(false);
+          boundingExtent([insideInner]))).to.be(false);
       });
 
     });
@@ -320,25 +320,25 @@ describe('ol/geom/Polygon', function() {
 
       it('does not intersect outside extent', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([outsideOuter]))).to.be(false);
+          boundingExtent([outsideOuter]))).to.be(false);
       });
 
       it('does intersect inside extent', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([inside]))).to.be(true);
+          boundingExtent([inside]))).to.be(true);
       });
 
       it('does intersect boundary extent', function() {
         const firstMidX = (outerRing[0][0] + outerRing[1][0]) / 2;
         const firstMidY = (outerRing[0][1] + outerRing[1][1]) / 2;
 
-        expect(polygon.intersectsExtent(_ol_extent_.boundingExtent([[firstMidX,
+        expect(polygon.intersectsExtent(boundingExtent([[firstMidX,
           firstMidY]]))).to.be(true);
       });
 
       it('does not intersect extent fully contained by inner ring', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([insideInner]))).to.be(false);
+          boundingExtent([insideInner]))).to.be(false);
       });
 
     });
@@ -427,27 +427,27 @@ describe('ol/geom/Polygon', function() {
 
       it('does not intersect outside extent', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([outsideOuter]))).to.be(false);
+          boundingExtent([outsideOuter]))).to.be(false);
       });
 
       it('does intersect inside extent', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([inside]))).to.be(true);
+          boundingExtent([inside]))).to.be(true);
       });
 
       it('does intersect boundary extent', function() {
         const firstMidX = (outerRing[0][0] + outerRing[1][0]) / 2;
         const firstMidY = (outerRing[0][1] + outerRing[1][1]) / 2;
 
-        expect(polygon.intersectsExtent(_ol_extent_.boundingExtent([[firstMidX,
+        expect(polygon.intersectsExtent(boundingExtent([[firstMidX,
           firstMidY]]))).to.be(true);
       });
 
       it('does not intersect extent fully contained by inner ring', function() {
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([insideInner1]))).to.be(false);
+          boundingExtent([insideInner1]))).to.be(false);
         expect(polygon.intersectsExtent(
-          _ol_extent_.boundingExtent([insideInner2]))).to.be(false);
+          boundingExtent([insideInner2]))).to.be(false);
       });
 
     });
diff --git a/test/spec/ol/interaction/dragzoom.test.js b/test/spec/ol/interaction/dragzoom.test.js
index d8c35a9585..8a5c2447f5 100644
--- a/test/spec/ol/interaction/dragzoom.test.js
+++ b/test/spec/ol/interaction/dragzoom.test.js
@@ -1,6 +1,6 @@
 import Map from '../../../../src/ol/Map.js';
 import View from '../../../../src/ol/View.js';
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {getCenter} from '../../../../src/ol/extent.js';
 import {fromExtent as polygonFromExtent} from '../../../../src/ol/geom/Polygon.js';
 import DragZoom from '../../../../src/ol/interaction/DragZoom.js';
 import VectorLayer from '../../../../src/ol/layer/Vector.js';
@@ -79,7 +79,7 @@ describe('ol.interaction.DragZoom', function() {
       setTimeout(function() {
         const view = map.getView();
         const center = view.getCenter();
-        expect(center).to.eql(_ol_extent_.getCenter(extent));
+        expect(center).to.eql(getCenter(extent));
         done();
       }, 50);
 
diff --git a/test/spec/ol/layer/group.test.js b/test/spec/ol/layer/group.test.js
index fbe7c6a950..014faced67 100644
--- a/test/spec/ol/layer/group.test.js
+++ b/test/spec/ol/layer/group.test.js
@@ -1,7 +1,7 @@
 import {getUid} from '../../../../src/ol/index.js';
 import {stableSort} from '../../../../src/ol/array.js';
 import Collection from '../../../../src/ol/Collection.js';
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {getIntersection} from '../../../../src/ol/extent.js';
 import LayerGroup from '../../../../src/ol/layer/Group.js';
 import Layer from '../../../../src/ol/layer/Layer.js';
 import {assign} from '../../../../src/ol/obj.js';
@@ -403,7 +403,7 @@ describe('ol.layer.Group', function() {
       });
       const layerStatesArray = layerGroup.getLayerStatesArray();
       expect(layerStatesArray[0].extent).to.eql(
-        _ol_extent_.getIntersection(layer3.getExtent(), groupExtent));
+        getIntersection(layer3.getExtent(), groupExtent));
       layerGroup.dispose();
     });
 
diff --git a/test/spec/ol/renderer/canvas/vectorlayer.test.js b/test/spec/ol/renderer/canvas/vectorlayer.test.js
index 5058a98254..b20d07e66f 100644
--- a/test/spec/ol/renderer/canvas/vectorlayer.test.js
+++ b/test/spec/ol/renderer/canvas/vectorlayer.test.js
@@ -2,7 +2,7 @@ import {getUid} from '../../../../../src/ol/index.js';
 import Feature from '../../../../../src/ol/Feature.js';
 import Map from '../../../../../src/ol/Map.js';
 import View from '../../../../../src/ol/View.js';
-import * as _ol_extent_ from '../../../../../src/ol/extent.js';
+import {buffer as bufferExtent, getWidth} from '../../../../../src/ol/extent.js';
 import Point from '../../../../../src/ol/geom/Point.js';
 import VectorLayer from '../../../../../src/ol/layer/Vector.js';
 import {clear} from '../../../../../src/ol/obj.js';
@@ -228,7 +228,7 @@ describe('ol.renderer.canvas.VectorLayer', function() {
       renderer = new CanvasVectorLayerRenderer(layer);
       const projection = getProjection('EPSG:3857');
       projExtent = projection.getExtent();
-      worldWidth = _ol_extent_.getWidth(projExtent);
+      worldWidth = getWidth(projExtent);
       buffer = layer.getRenderBuffer();
       frameState = {
         skippedFeatureUids: {},
@@ -246,7 +246,7 @@ describe('ol.renderer.canvas.VectorLayer', function() {
       frameState.extent =
           [projExtent[0] - 10000, -10000, projExtent[0] + 10000, 10000];
       renderer.prepareFrame(frameState, {});
-      expect(renderer.replayGroup_.maxExtent_).to.eql(_ol_extent_.buffer([
+      expect(renderer.replayGroup_.maxExtent_).to.eql(bufferExtent([
         projExtent[0] - worldWidth + buffer,
         -10000, projExtent[2] + worldWidth - buffer, 10000
       ], buffer));
@@ -258,7 +258,7 @@ describe('ol.renderer.canvas.VectorLayer', function() {
       frameState.extent =
           [projExtent[0] - 10000, -10000, projExtent[1] - 10000, 10000];
       renderer.prepareFrame(frameState, {});
-      expect(renderer.replayGroup_.maxExtent_).to.eql(_ol_extent_.buffer([
+      expect(renderer.replayGroup_.maxExtent_).to.eql(bufferExtent([
         projExtent[0] - worldWidth + buffer,
         -10000, projExtent[2] + worldWidth - buffer, 10000
       ], buffer));
@@ -269,7 +269,7 @@ describe('ol.renderer.canvas.VectorLayer', function() {
       frameState.extent =
           [2 * projExtent[0] - 10000, -10000, 2 * projExtent[1] + 10000, 10000];
       renderer.prepareFrame(frameState, {});
-      expect(renderer.replayGroup_.maxExtent_).to.eql(_ol_extent_.buffer([
+      expect(renderer.replayGroup_.maxExtent_).to.eql(bufferExtent([
         projExtent[0] - worldWidth + buffer,
         -10000, projExtent[2] + worldWidth - buffer, 10000
       ], buffer));
@@ -282,7 +282,7 @@ describe('ol.renderer.canvas.VectorLayer', function() {
         -10000, projExtent[1] + 2 * worldWidth + 10000, 10000
       ];
       renderer.prepareFrame(frameState, {});
-      expect(renderer.replayGroup_.maxExtent_).to.eql(_ol_extent_.buffer([
+      expect(renderer.replayGroup_.maxExtent_).to.eql(bufferExtent([
         projExtent[0] - 2 * worldWidth - 10000,
         -10000, projExtent[2] + 2 * worldWidth + 10000, 10000
       ], buffer));
diff --git a/test/spec/ol/renderer/canvas/vectortilelayer.test.js b/test/spec/ol/renderer/canvas/vectortilelayer.test.js
index 044507a17a..8780c063a7 100644
--- a/test/spec/ol/renderer/canvas/vectortilelayer.test.js
+++ b/test/spec/ol/renderer/canvas/vectortilelayer.test.js
@@ -6,7 +6,7 @@ import TileState from '../../../../../src/ol/TileState.js';
 import VectorImageTile from '../../../../../src/ol/VectorImageTile.js';
 import VectorTile from '../../../../../src/ol/VectorTile.js';
 import View from '../../../../../src/ol/View.js';
-import * as _ol_extent_ from '../../../../../src/ol/extent.js';
+import {getCenter} from '../../../../../src/ol/extent.js';
 import MVT from '../../../../../src/ol/format/MVT.js';
 import Point from '../../../../../src/ol/geom/Point.js';
 import VectorTileLayer from '../../../../../src/ol/layer/VectorTile.js';
@@ -364,7 +364,7 @@ describe('ol.renderer.canvas.VectorTileLayer', function() {
           })
         ],
         view: new View({
-          center: _ol_extent_.getCenter(extent),
+          center: getCenter(extent),
           zoom: 19
         })
       });
diff --git a/test/spec/ol/tilegrid/tilegrid.test.js b/test/spec/ol/tilegrid/tilegrid.test.js
index 6e77f340ff..2db2c7fa21 100644
--- a/test/spec/ol/tilegrid/tilegrid.test.js
+++ b/test/spec/ol/tilegrid/tilegrid.test.js
@@ -1,6 +1,6 @@
 import {DEFAULT_MAX_ZOOM, DEFAULT_TILE_SIZE} from '../../../../src/ol/tilegrid/common.js';
 import TileRange from '../../../../src/ol/TileRange.js';
-import * as _ol_extent_ from '../../../../src/ol/extent.js';
+import {createOrUpdate} from '../../../../src/ol/extent.js';
 import {get as getProjection, METERS_PER_UNIT} from '../../../../src/ol/proj.js';
 import {HALF_SIZE} from '../../../../src/ol/proj/epsg3857.js';
 import Projection from '../../../../src/ol/proj/Projection.js';
@@ -275,7 +275,7 @@ describe('ol.tilegrid.TileGrid', function() {
 
   describe('createForExtent', function() {
     it('allows creation of tile grid from extent', function() {
-      const extent = _ol_extent_.createOrUpdate(-100, -100, 100, 100);
+      const extent = createOrUpdate(-100, -100, 100, 100);
       const grid = createForExtent(extent);
       expect(grid).to.be.a(TileGrid);
 
diff --git a/test/spec/ol/view.test.js b/test/spec/ol/view.test.js
index 678a374ec1..c024db66b0 100644
--- a/test/spec/ol/view.test.js
+++ b/test/spec/ol/view.test.js
@@ -1,7 +1,7 @@
 import Map from '../../../src/ol/Map.js';
 import View, {createCenterConstraint, createResolutionConstraint, createRotationConstraint} from '../../../src/ol/View.js';
 import ViewHint from '../../../src/ol/ViewHint.js';
-import * as _ol_extent_ from '../../../src/ol/extent.js';
+import {createEmpty} from '../../../src/ol/extent.js';
 import Circle from '../../../src/ol/geom/Circle.js';
 import LineString from '../../../src/ol/geom/LineString.js';
 import Point from '../../../src/ol/geom/Point.js';
@@ -1348,7 +1348,7 @@ describe('ol.View', function() {
     });
     it('throws on empty extent', function() {
       expect(function() {
-        view.fit(_ol_extent_.createEmpty());
+        view.fit(createEmpty());
       }).to.throwException();
     });
     it('animates when duration is defined', function(done) {