Remove module level references to window and document (close snowplow#928)

Author: Paul Boocock

common/changes/@snowplow/browser-plugin-browser-features/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-plugin-browser-features"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-browser-features",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/browser-plugin-error-tracking/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-plugin-error-tracking"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-error-tracking",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/browser-plugin-optimizely-x/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-plugin-optimizely-x"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-optimizely-x",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/browser-plugin-optimizely/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-plugin-optimizely"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-optimizely",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/browser-plugin-parrable/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-plugin-parrable"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-parrable",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/browser-plugin-performance-timing/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-plugin-performance-timing"
+    }
+  ],
+  "packageName": "@snowplow/browser-plugin-performance-timing",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/browser-tracker-core/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-tracker-core"
+    }
+  ],
+  "packageName": "@snowplow/browser-tracker-core",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/browser-tracker/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/browser-tracker"
+    }
+  ],
+  "packageName": "@snowplow/browser-tracker",
+  "email": "paul@snowplowanalytics.com"
+}

common/changes/@snowplow/javascript-tracker/issue-928_2021-03-22-13-57.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "comment": "Remove module level references to window and document (close #928)",
+      "type": "none",
+      "packageName": "@snowplow/javascript-tracker"
+    }
+  ],
+  "packageName": "@snowplow/javascript-tracker",
+  "email": "paul@snowplowanalytics.com"
+}

libraries/browser-tracker-core/src/detectors.ts

@@ -28,17 +28,14 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-const windowAlias = window,
-  documentAlias = document;
-
 /*
  * Checks whether sessionStorage is available, in a way that
  * does not throw a SecurityError in Firefox if "always ask"
  * is enabled for cookies (https://github.com/snowplow/snowplow/issues/163).
  */
 export function hasSessionStorage() {
   try {
-    return !!windowAlias.sessionStorage;
+    return !!window.sessionStorage;
   } catch (e) {
     return true; // SecurityError when referencing it means it exists
   }
@@ -51,7 +48,7 @@ export function hasSessionStorage() {
  */
 export function hasLocalStorage() {
   try {
-    return !!windowAlias.localStorage;
+    return !!window.localStorage;
   } catch (e) {
     return true; // SecurityError when referencing it means it exists
   }
@@ -68,8 +65,9 @@ export function localStorageAccessible() {
     return false;
   }
   try {
-    windowAlias.localStorage.setItem(mod, mod);
-    windowAlias.localStorage.removeItem(mod);
+    const ls = window.localStorage;
+    ls.setItem(mod, mod);
+    ls.removeItem(mod);
     return true;
   } catch (e) {
     return false;
@@ -86,11 +84,11 @@ export function localStorageAccessible() {
 export function detectViewport() {
   var width, height;
 
-  if ('innerWidth' in windowAlias) {
-    width = windowAlias['innerWidth'];
-    height = windowAlias['innerHeight'];
+  if ('innerWidth' in window) {
+    width = window['innerWidth'];
+    height = window['innerHeight'];
   } else {
-    const e = documentAlias.documentElement || documentAlias.body;
+    const e = document.documentElement || document.body;
     width = e['clientWidth'];
     height = e['clientHeight'];
   }
@@ -110,8 +108,8 @@ export function detectViewport() {
  * - http://andylangton.co.uk/articles/javascript/get-viewport-size-javascript/
  */
 export function detectDocumentSize() {
-  var de = documentAlias.documentElement, // Alias
-    be = documentAlias.body,
+  var de = document.documentElement, // Alias
+    be = document.body,
     // document.body may not have rendered, so check whether be.offsetHeight is null
     bodyHeight = be ? Math.max(be.offsetHeight, be.scrollHeight) : 0;
   var w = Math.max(de.clientWidth, de.offsetWidth, de.scrollWidth);