Merge pull request #24 from mrjones2014/feature/browser-utils

add BrowserUtils.isIE() method

Author: wintondeshong

src/utilities/browser-utils.test.ts

@@ -0,0 +1,54 @@
+import { BrowserUtils } from "./browser-utils";
+
+describe("BrowserUtils", () => {
+  describe("isIE", () => {
+    it("when wondow.document.documentMode is undefined, then returns false", () => {
+      // Arrange
+      window.document.documentMode = undefined;
+
+      // Act
+      const result = BrowserUtils.isIE();
+
+      // Assert
+      expect(result).toBeFalse();
+    });
+
+    it("when window.document.documentMode is truthy, then returns true", () => {
+      // Arrange
+      window.document.documentMode = true;
+
+      // Act
+      const result = BrowserUtils.isIE();
+
+      // Assert
+      expect(result).toBeTrue();
+    });
+  });
+
+  describe("isNotIE", () => {
+    it("when wondow.document.documentMode is undefined, then returns true", () => {
+      // Arrange
+      window.document.documentMode = undefined;
+
+      // Act
+      const result = BrowserUtils.isNotIE();
+
+      // Assert
+      expect(result).toBeTrue();
+    });
+
+    it("when window.document.documentMode is truthy, then returns false", () => {
+      // Arrange
+      window.document.documentMode = true;
+
+      // Act
+      const result = BrowserUtils.isNotIE();
+
+      // Assert
+      expect(result).toBeFalse();
+    });
+  });
+
+  // Clean up
+  window.document.documentMode = undefined;
+});

src/utilities/browser-utils.ts

@@ -0,0 +1,27 @@
+/**
+ * Allows us to use the documentMode for feature detection on globalThis.Document
+ */
+declare global {
+  interface Document {
+      documentMode?: any;
+  }
+}
+
+/**
+* Returns true if the detected browser is Internet Explorer.
+* @returns boolean
+*/
+const _isIE = (): boolean => {
+  return /*@cc_on!@*/ false || !!document.documentMode;
+};
+
+/**
+ * Returns true if the brower is NOT Internet Explorer.
+ * @returns boolean
+ */
+const _isNotIE = (): boolean => !_isIE();
+
+export const BrowserUtils = {
+  isIE: _isIE,
+  isNotIE: _isNotIE,
+};