fix(formatNumber): format null value as empty string (#20)

* fix(formatNumber): format null value as empty string

* chore(travis-ci): upgrade node.js version

Author: ggkrustev

.travis.yml

@@ -13,7 +13,7 @@ cache:
 notifications:
   email: false
 node_js:
-  - '4'
+  - '6'
 before_install:
   - npm i -g npm@^3.8.0
   - export CHROME_BIN=/usr/bin/google-chrome

src/numbers/format-number.js

@@ -46,7 +46,7 @@ function getFormatOptions(format) {
 }
 
 export default function formatNumber(number, format = "n", locale = "en") {
-    if (number === undefined) {
+    if (number === undefined || number === null) {
         return "";
     }
 

test/numbers.js

@@ -43,10 +43,14 @@ describe('formatNumber', () => {
         expect(formatNumber(10000)).toEqual("10,000");
     });
 
-    it('should return empty string if not value is passed', () => {
+    it('should return empty string if no value is passed', () => {
         expect(formatNumber()).toEqual("");
     });
 
+    it('should return empty string if null value is passed', () => {
+        expect(formatNumber(null)).toEqual("");
+    });
+
     it('should return value if not finite value is passed', () => {
         expect(formatNumber(Infinity)).toBe(Infinity);
         expect(formatNumber("foo")).toEqual("foo");
@@ -621,4 +625,4 @@ describe('parseNumber', () => {
             }).not.toThrow();
         });
     });
-});
+});