diff --git a/src/ol/color/color.js b/src/ol/color/color.js
index 105fe5e387..35c362e731 100644
--- a/src/ol/color/color.js
+++ b/src/ol/color/color.js
@@ -106,7 +106,7 @@ ol.color.asArray = function(color) {
   if (goog.isArray(color)) {
     return color;
   } else {
-    goog.asserts.assert(goog.isString(color), 'Color should be a string');
+    goog.asserts.assert(typeof color === 'string', 'Color should be a string');
     return ol.color.fromString(color);
   }
 };
@@ -119,7 +119,7 @@ ol.color.asArray = function(color) {
  * @api
  */
 ol.color.asString = function(color) {
-  if (goog.isString(color)) {
+  if (typeof color === 'string') {
     return color;
   } else {
     goog.asserts.assert(goog.isArray(color), 'Color should be an array');
@@ -322,10 +322,10 @@ ol.color.stringOrColorEquals = function(color1, color2) {
   if (color1 === color2 || color1 == color2) {
     return true;
   }
-  if (goog.isString(color1)) {
+  if (typeof color1 === 'string') {
     color1 = ol.color.fromString(color1);
   }
-  if (goog.isString(color2)) {
+  if (typeof color2 === 'string') {
     color2 = ol.color.fromString(color2);
   }
   return ol.color.equals(color1, color2);
diff --git a/src/ol/control/attributioncontrol.js b/src/ol/control/attributioncontrol.js
index d583bbfca8..7795f29cfa 100644
--- a/src/ol/control/attributioncontrol.js
+++ b/src/ol/control/attributioncontrol.js
@@ -74,7 +74,7 @@ ol.control.Attribution = function(opt_options) {
    * @private
    * @type {Node}
    */
-  this.collapseLabel_ = goog.isString(collapseLabel) ?
+  this.collapseLabel_ = typeof collapseLabel === 'string' ?
       goog.dom.createDom('SPAN', {}, collapseLabel) :
       collapseLabel;
 
@@ -84,7 +84,7 @@ ol.control.Attribution = function(opt_options) {
    * @private
    * @type {Node}
    */
-  this.label_ = goog.isString(label) ?
+  this.label_ = typeof label === 'string' ?
       goog.dom.createDom('SPAN', {}, label) :
       label;
 
diff --git a/src/ol/control/fullscreencontrol.js b/src/ol/control/fullscreencontrol.js
index af7a210437..0086d93339 100644
--- a/src/ol/control/fullscreencontrol.js
+++ b/src/ol/control/fullscreencontrol.js
@@ -45,7 +45,7 @@ ol.control.FullScreen = function(opt_options) {
    * @private
    * @type {Node}
    */
-  this.labelNode_ = goog.isString(label) ?
+  this.labelNode_ = typeof label === 'string' ?
       document.createTextNode(label) : label;
 
   var labelActive = options.labelActive ? options.labelActive : '\u00d7';
@@ -54,7 +54,7 @@ ol.control.FullScreen = function(opt_options) {
    * @private
    * @type {Node}
    */
-  this.labelActiveNode_ = goog.isString(labelActive) ?
+  this.labelActiveNode_ = typeof labelActive === 'string' ?
       document.createTextNode(labelActive) : labelActive;
 
   var tipLabel = options.tipLabel ? options.tipLabel : 'Toggle full-screen';
diff --git a/src/ol/control/overviewmapcontrol.js b/src/ol/control/overviewmapcontrol.js
index 33e4a6a6d5..f050779dc9 100644
--- a/src/ol/control/overviewmapcontrol.js
+++ b/src/ol/control/overviewmapcontrol.js
@@ -62,7 +62,7 @@ ol.control.OverviewMap = function(opt_options) {
    * @private
    * @type {Node}
    */
-  this.collapseLabel_ = goog.isString(collapseLabel) ?
+  this.collapseLabel_ = typeof collapseLabel === 'string' ?
       goog.dom.createDom('SPAN', {}, collapseLabel) :
       collapseLabel;
 
@@ -72,7 +72,7 @@ ol.control.OverviewMap = function(opt_options) {
    * @private
    * @type {Node}
    */
-  this.label_ = goog.isString(label) ?
+  this.label_ = typeof label === 'string' ?
       goog.dom.createDom('SPAN', {}, label) :
       label;
 
diff --git a/src/ol/control/rotatecontrol.js b/src/ol/control/rotatecontrol.js
index 127a22c97d..38e1375bde 100644
--- a/src/ol/control/rotatecontrol.js
+++ b/src/ol/control/rotatecontrol.js
@@ -36,7 +36,7 @@ ol.control.Rotate = function(opt_options) {
    */
   this.label_ = null;
 
-  if (goog.isString(label)) {
+  if (typeof label === 'string') {
     this.label_ = goog.dom.createDom('SPAN',
         'ol-compass', label);
   } else {
diff --git a/src/ol/events/eventtarget.js b/src/ol/events/eventtarget.js
index 3f7b6fcb36..b103a25e8c 100644
--- a/src/ol/events/eventtarget.js
+++ b/src/ol/events/eventtarget.js
@@ -59,7 +59,7 @@ ol.events.EventTarget.prototype.addEventListener = function(type, listener) {
  *     event object or if any of the listeners returned false.
  */
 ol.events.EventTarget.prototype.dispatchEvent = function(event) {
-  var evt = goog.isString(event) ? new ol.events.Event(event) : event;
+  var evt = typeof event === 'string' ? new ol.events.Event(event) : event;
   var type = evt.type;
   evt.target = this;
   var listeners = this.listeners_[type];
diff --git a/src/ol/format/gml/gmlbaseformat.js b/src/ol/format/gml/gmlbaseformat.js
index 77cd3aeb9f..b80a47935b 100644
--- a/src/ol/format/gml/gmlbaseformat.js
+++ b/src/ol/format/gml/gmlbaseformat.js
@@ -143,7 +143,7 @@ ol.format.GMLBase.prototype.readFeaturesInternal = function(node, objectStack) {
       context['featureType'] = featureType;
       context['featureNS'] = featureNS;
     }
-    if (goog.isString(featureNS)) {
+    if (typeof featureNS === 'string') {
       var ns = featureNS;
       featureNS = {};
       featureNS[defaultPrefix] = ns;
diff --git a/src/ol/format/jsonfeatureformat.js b/src/ol/format/jsonfeatureformat.js
index a967b745e9..331d41409c 100644
--- a/src/ol/format/jsonfeatureformat.js
+++ b/src/ol/format/jsonfeatureformat.js
@@ -29,7 +29,7 @@ goog.inherits(ol.format.JSONFeature, ol.format.Feature);
 ol.format.JSONFeature.prototype.getObject_ = function(source) {
   if (goog.isObject(source)) {
     return source;
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var object = goog.json.parse(source);
     return object ? object : null;
   } else {
diff --git a/src/ol/format/kmlformat.js b/src/ol/format/kmlformat.js
index 79af2fa670..a8eebea2a7 100644
--- a/src/ol/format/kmlformat.js
+++ b/src/ol/format/kmlformat.js
@@ -431,7 +431,7 @@ ol.format.KML.createFeatureStyleFunction_ = function(style, styleUrl,
 ol.format.KML.findStyle_ = function(styleValue, defaultStyle, sharedStyles) {
   if (goog.isArray(styleValue)) {
     return styleValue;
-  } else if (goog.isString(styleValue)) {
+  } else if (typeof styleValue === 'string') {
     // KML files in the wild occasionally forget the leading `#` on styleUrls
     // defined in the same document.  Add a leading `#` if it enables to find
     // a style.
@@ -1274,7 +1274,7 @@ ol.format.KML.PlacemarkStyleMapParser_ = function(node, objectStack) {
       'placemarkObject should be an Object');
   if (goog.isArray(styleMapValue)) {
     placemarkObject['Style'] = styleMapValue;
-  } else if (goog.isString(styleMapValue)) {
+  } else if (typeof styleMapValue === 'string') {
     placemarkObject['styleUrl'] = styleMapValue;
   } else {
     goog.asserts.fail('styleMapValue has an unknown type');
@@ -1973,7 +1973,7 @@ ol.format.KML.prototype.readName = function(source) {
     return this.readNameFromDocument(/** @type {Document} */ (source));
   } else if (ol.xml.isNode(source)) {
     return this.readNameFromNode(/** @type {Node} */ (source));
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readNameFromDocument(doc);
   } else {
@@ -2045,7 +2045,7 @@ ol.format.KML.prototype.readNetworkLinks = function(source) {
   } else if (ol.xml.isNode(source)) {
     ol.array.extend(networkLinks, this.readNetworkLinksFromNode(
         /** @type {Node} */ (source)));
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     ol.array.extend(networkLinks, this.readNetworkLinksFromDocument(doc));
   } else {
diff --git a/src/ol/format/textfeatureformat.js b/src/ol/format/textfeatureformat.js
index fc1bddc273..7c86d92a50 100644
--- a/src/ol/format/textfeatureformat.js
+++ b/src/ol/format/textfeatureformat.js
@@ -26,7 +26,7 @@ goog.inherits(ol.format.TextFeature, ol.format.Feature);
  * @return {string} Text.
  */
 ol.format.TextFeature.prototype.getText_ = function(source) {
-  if (goog.isString(source)) {
+  if (typeof source === 'string') {
     return source;
   } else {
     goog.asserts.fail();
diff --git a/src/ol/format/wfsformat.js b/src/ol/format/wfsformat.js
index 325e5a9bf6..0985637b74 100644
--- a/src/ol/format/wfsformat.js
+++ b/src/ol/format/wfsformat.js
@@ -151,7 +151,7 @@ ol.format.WFS.prototype.readTransactionResponse = function(source) {
         /** @type {Document} */ (source));
   } else if (ol.xml.isNode(source)) {
     return this.readTransactionResponseFromNode(/** @type {Node} */ (source));
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readTransactionResponseFromDocument(doc);
   } else {
@@ -176,7 +176,7 @@ ol.format.WFS.prototype.readFeatureCollectionMetadata = function(source) {
   } else if (ol.xml.isNode(source)) {
     return this.readFeatureCollectionMetadataFromNode(
         /** @type {Node} */ (source));
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readFeatureCollectionMetadataFromDocument(doc);
   } else {
diff --git a/src/ol/format/xmlfeatureformat.js b/src/ol/format/xmlfeatureformat.js
index 49e3288258..cbee017f33 100644
--- a/src/ol/format/xmlfeatureformat.js
+++ b/src/ol/format/xmlfeatureformat.js
@@ -42,7 +42,7 @@ ol.format.XMLFeature.prototype.readFeature = function(source, opt_options) {
         /** @type {Document} */ (source), opt_options);
   } else if (ol.xml.isNode(source)) {
     return this.readFeatureFromNode(/** @type {Node} */ (source), opt_options);
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readFeatureFromDocument(doc, opt_options);
   } else {
@@ -85,7 +85,7 @@ ol.format.XMLFeature.prototype.readFeatures = function(source, opt_options) {
         /** @type {Document} */ (source), opt_options);
   } else if (ol.xml.isNode(source)) {
     return this.readFeaturesFromNode(/** @type {Node} */ (source), opt_options);
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readFeaturesFromDocument(doc, opt_options);
   } else {
@@ -133,7 +133,7 @@ ol.format.XMLFeature.prototype.readGeometry = function(source, opt_options) {
         /** @type {Document} */ (source), opt_options);
   } else if (ol.xml.isNode(source)) {
     return this.readGeometryFromNode(/** @type {Node} */ (source), opt_options);
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readGeometryFromDocument(doc, opt_options);
   } else {
@@ -169,7 +169,7 @@ ol.format.XMLFeature.prototype.readProjection = function(source) {
     return this.readProjectionFromDocument(/** @type {Document} */ (source));
   } else if (ol.xml.isNode(source)) {
     return this.readProjectionFromNode(/** @type {Node} */ (source));
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readProjectionFromDocument(doc);
   } else {
diff --git a/src/ol/format/xmlformat.js b/src/ol/format/xmlformat.js
index 48b18d9319..c5e0e2d330 100644
--- a/src/ol/format/xmlformat.js
+++ b/src/ol/format/xmlformat.js
@@ -23,7 +23,7 @@ ol.format.XML.prototype.read = function(source) {
     return this.readFromDocument(/** @type {Document} */ (source));
   } else if (ol.xml.isNode(source)) {
     return this.readFromNode(/** @type {Node} */ (source));
-  } else if (goog.isString(source)) {
+  } else if (typeof source === 'string') {
     var doc = ol.xml.parse(source);
     return this.readFromDocument(doc);
   } else {
diff --git a/src/ol/layer/heatmaplayer.js b/src/ol/layer/heatmaplayer.js
index 40d17252e3..26b8ebd764 100644
--- a/src/ol/layer/heatmaplayer.js
+++ b/src/ol/layer/heatmaplayer.js
@@ -94,7 +94,7 @@ ol.layer.Heatmap = function(opt_options) {
 
   var weight = options.weight ? options.weight : 'weight';
   var weightFunction;
-  if (goog.isString(weight)) {
+  if (typeof weight === 'string') {
     weightFunction = function(feature) {
       return feature.get(weight);
     };
diff --git a/src/ol/map.js b/src/ol/map.js
index fe05b5bf50..f9c1829064 100644
--- a/src/ol/map.js
+++ b/src/ol/map.js
@@ -1495,7 +1495,7 @@ ol.Map.createOptionsInternal = function(options) {
   if (options.keyboardEventTarget !== undefined) {
     // cannot use goog.dom.getElement because its argument cannot be
     // of type Document
-    keyboardEventTarget = goog.isString(options.keyboardEventTarget) ?
+    keyboardEventTarget = typeof options.keyboardEventTarget === 'string' ?
         document.getElementById(options.keyboardEventTarget) :
         options.keyboardEventTarget;
   }
@@ -1511,7 +1511,7 @@ ol.Map.createOptionsInternal = function(options) {
     logos[ol.OL3_LOGO_URL] = ol.OL3_URL;
   } else {
     var logo = options.logo;
-    if (goog.isString(logo)) {
+    if (typeof logo === 'string') {
       logos[logo] = '';
     } else if (goog.isObject(logo)) {
       goog.asserts.assertString(logo.href, 'logo.href should be a string');
@@ -1541,7 +1541,7 @@ ol.Map.createOptionsInternal = function(options) {
   if (options.renderer !== undefined) {
     if (goog.isArray(options.renderer)) {
       rendererTypes = options.renderer;
-    } else if (goog.isString(options.renderer)) {
+    } else if (typeof options.renderer === 'string') {
       rendererTypes = [options.renderer];
     } else {
       goog.asserts.fail('Incorrect format for renderer option');
diff --git a/src/ol/proj/proj.js b/src/ol/proj/proj.js
index 1c49ded408..5b3bd0b6e8 100644
--- a/src/ol/proj/proj.js
+++ b/src/ol/proj/proj.js
@@ -520,7 +520,7 @@ ol.proj.clearAllProjections = function() {
 ol.proj.createProjection = function(projection, defaultCode) {
   if (!projection) {
     return ol.proj.get(defaultCode);
-  } else if (goog.isString(projection)) {
+  } else if (typeof projection === 'string') {
     return ol.proj.get(projection);
   } else {
     goog.asserts.assertInstanceof(projection, ol.proj.Projection,
@@ -680,7 +680,7 @@ ol.proj.get = function(projectionLike) {
   var projection;
   if (projectionLike instanceof ol.proj.Projection) {
     projection = projectionLike;
-  } else if (goog.isString(projectionLike)) {
+  } else if (typeof projectionLike === 'string') {
     var code = projectionLike;
     projection = ol.proj.projections_[code];
     if (ol.ENABLE_PROJ4JS) {
diff --git a/src/ol/render/canvas/canvasreplay.js b/src/ol/render/canvas/canvasreplay.js
index 6b014add32..ebad793ceb 100644
--- a/src/ol/render/canvas/canvasreplay.js
+++ b/src/ol/render/canvas/canvasreplay.js
@@ -376,7 +376,7 @@ ol.render.canvas.Replay.prototype.replay_ = function(
         goog.asserts.assert(goog.isNumber(instruction[2]),
             '3rd instruction should be a number');
         dd = /** @type {number} */ (instruction[2]);
-        goog.asserts.assert(goog.isString(instruction[3]),
+        goog.asserts.assert(typeof instruction[3] === 'string',
             '4th instruction should be a string');
         text = /** @type {string} */ (instruction[3]);
         goog.asserts.assert(goog.isNumber(instruction[4]),
@@ -497,19 +497,19 @@ ol.render.canvas.Replay.prototype.replay_ = function(
         ++i;
         break;
       case ol.render.canvas.Instruction.SET_FILL_STYLE:
-        goog.asserts.assert(goog.isString(instruction[1]),
+        goog.asserts.assert(typeof instruction[1] === 'string',
             '2nd instruction should be a string');
         context.fillStyle = /** @type {string} */ (instruction[1]);
         ++i;
         break;
       case ol.render.canvas.Instruction.SET_STROKE_STYLE:
-        goog.asserts.assert(goog.isString(instruction[1]),
+        goog.asserts.assert(typeof instruction[1] === 'string',
             '2nd instruction should be a string');
         goog.asserts.assert(goog.isNumber(instruction[2]),
             '3rd instruction should be a number');
-        goog.asserts.assert(goog.isString(instruction[3]),
+        goog.asserts.assert(typeof instruction[3] === 'string',
             '4rd instruction should be a string');
-        goog.asserts.assert(goog.isString(instruction[4]),
+        goog.asserts.assert(typeof instruction[4] === 'string',
             '5th instruction should be a string');
         goog.asserts.assert(goog.isNumber(instruction[5]),
             '6th instruction should be a number');
@@ -531,11 +531,11 @@ ol.render.canvas.Replay.prototype.replay_ = function(
         ++i;
         break;
       case ol.render.canvas.Instruction.SET_TEXT_STYLE:
-        goog.asserts.assert(goog.isString(instruction[1]),
+        goog.asserts.assert(typeof instruction[1] === 'string',
             '2nd instruction should be a string');
-        goog.asserts.assert(goog.isString(instruction[2]),
+        goog.asserts.assert(typeof instruction[2] === 'string',
             '3rd instruction should be a string');
-        goog.asserts.assert(goog.isString(instruction[3]),
+        goog.asserts.assert(typeof instruction[3] === 'string',
             '4th instruction should be a string');
         context.font = /** @type {string} */ (instruction[1]);
         context.textAlign = /** @type {string} */ (instruction[2]);
diff --git a/src/ol/renderer/layerrenderer.js b/src/ol/renderer/layerrenderer.js
index 6bb4ba492a..bab2159aa7 100644
--- a/src/ol/renderer/layerrenderer.js
+++ b/src/ol/renderer/layerrenderer.js
@@ -222,7 +222,7 @@ ol.renderer.Layer.prototype.updateAttributions = function(attributionsSet, attri
 ol.renderer.Layer.prototype.updateLogos = function(frameState, source) {
   var logo = source.getLogo();
   if (logo !== undefined) {
-    if (goog.isString(logo)) {
+    if (typeof logo === 'string') {
       frameState.logos[logo] = '';
     } else if (goog.isObject(logo)) {
       goog.asserts.assertString(logo.href, 'logo.href is a string');
diff --git a/src/ol/source/tileutfgridsource.js b/src/ol/source/tileutfgridsource.js
index 7a2e335fbd..22d7b2b9dd 100644
--- a/src/ol/source/tileutfgridsource.js
+++ b/src/ol/source/tileutfgridsource.js
@@ -277,7 +277,7 @@ ol.source.TileUTFGridTile_.prototype.getData = function(coordinate) {
 
   var row = this.grid_[Math.floor((1 - yRelative) * this.grid_.length)];
 
-  if (!goog.isString(row)) {
+  if (typeof row !== 'string') {
     return null;
   }
 
diff --git a/src/ol/style/style.js b/src/ol/style/style.js
index a494d2d62a..7ee8039d08 100644
--- a/src/ol/style/style.js
+++ b/src/ol/style/style.js
@@ -159,7 +159,7 @@ ol.style.Style.prototype.getZIndex = function() {
 ol.style.Style.prototype.setGeometry = function(geometry) {
   if (goog.isFunction(geometry)) {
     this.geometryFunction_ = geometry;
-  } else if (goog.isString(geometry)) {
+  } else if (typeof geometry === 'string') {
     this.geometryFunction_ = function(feature) {
       var result = feature.get(geometry);
       if (result) {