diff --git a/src/util/dom.ts b/src/util/dom.ts
index 439e50d000..a3d7d8a43c 100644
--- a/src/util/dom.ts
+++ b/src/util/dom.ts
@@ -83,7 +83,7 @@ export function zoneRafFrames(framesToWait: number, callback: Function) {
   }
 }
 
-export let CSS: {
+export const CSS: {
   transform?: string,
   transition?: string,
   transitionDuration?: string,
@@ -255,7 +255,7 @@ export function isTextInput(ele: any) {
 }
 
 export function hasFocusedTextInput() {
-  let ele = <HTMLElement>document.activeElement;
+  const ele = <HTMLElement>document.activeElement;
   if (isTextInput(ele)) {
     return (ele.parentElement.querySelector(':focus') === ele);
   }
diff --git a/src/util/test/dom.spec.ts b/src/util/test/dom.spec.ts
new file mode 100644
index 0000000000..f4208cb84e
--- /dev/null
+++ b/src/util/test/dom.spec.ts
@@ -0,0 +1,160 @@
+import * as dom from '../dom';
+
+
+describe('dom', () => {
+
+  describe('isTextInput', () => {
+
+    it('should return false if input[type=button]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'button';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=checkbox]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'checkbox';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=color]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'color';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=file]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'file';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=image]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'image';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=radio]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'radio';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=range]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'range';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=reset]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'reset';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if input[type=submit]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'submit';
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return true if input date', () => {
+      const ele = document.createElement('input');
+      ele.type = 'date';
+      expect(dom.isTextInput(ele)).toBe(true);
+
+      ele.type = 'datetime';
+      expect(dom.isTextInput(ele)).toBe(true);
+
+      ele.type = 'datetime-local';
+      expect(dom.isTextInput(ele)).toBe(true);
+
+      ele.type = 'month';
+      expect(dom.isTextInput(ele)).toBe(true);
+
+      ele.type = 'time';
+      expect(dom.isTextInput(ele)).toBe(true);
+
+      ele.type = 'week';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=email]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'email';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=number]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'number';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=number]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'number';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=password]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'password';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=search]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'search';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=tel]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'tel';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=url]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'url';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input[type=text]', () => {
+      const ele = document.createElement('input');
+      ele.type = 'text';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if input and unknown type', () => {
+      const ele = document.createElement('input');
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if contentEditable', () => {
+      const ele = document.createElement('div');
+      ele.contentEditable = 'true';
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return true if textarea', () => {
+      const ele = document.createElement('textarea');
+      expect(dom.isTextInput(ele)).toBe(true);
+    });
+
+    it('should return false if a div', () => {
+      const ele = document.createElement('div');
+      expect(dom.isTextInput(ele)).toBe(false);
+    });
+
+    it('should return false if blank', () => {
+      expect(dom.isTextInput(null)).toBe(false);
+      expect(dom.isTextInput(undefined)).toBe(false);
+      expect(dom.isTextInput(false)).toBe(false);
+    });
+
+  });
+
+});