feat(util): add string byte size function

Author: rhyslbw

Diff for: packages/util/src/index.ts

@@ -16,6 +16,7 @@ export * from './opaqueTypes';
 export * from './environment';
 export * from './patchObject';
 export * from './isPromise';
+export * from './string';
 export * from './transformer';
 export * from './Percent';
 export * from './util';

Diff for: packages/util/src/string.ts

@@ -0,0 +1,3 @@
+export const StringUtils = {
+  byteSize: (str: string) => new Blob([str]).size
+};

Diff for: packages/util/test/string.test.ts

@@ -0,0 +1,13 @@
+import { StringUtils } from '../src';
+
+// Test vectors sourced from https://www.javainuse.com/bytesize
+
+describe('StringUtils', () => {
+  describe('byteSize', () => {
+    it('returns the byte size of the string', () => {
+      expect(StringUtils.byteSize('The quick brown fox jumps over the lazy dog')).toEqual(43);
+      expect(StringUtils.byteSize('helloWorld!')).toEqual(11);
+      expect(StringUtils.byteSize('👋')).toEqual(4);
+    });
+  });
+});