diff --git a/ReadMe.md b/ReadMe.md
index de22e4c..47d5bd3 100644
--- a/ReadMe.md
+++ b/ReadMe.md
@@ -145,10 +145,10 @@ Currently covered:
 
 - FormatBytes
 - MathHelpers
+- StringHelpers
+- UniqIdGenerators (Part)
+- UrlParser
 
 TODO:
 
 - JavaScriptHelpers
-- StringHelpers
-- UniqIdGenerators
-- UrlParser
diff --git a/build/test.html b/build/test.html
index 75b06c1..7c3d739 100644
--- a/build/test.html
+++ b/build/test.html
@@ -14,28 +14,6 @@
 </body>
 <script languagae="JavaScript">
 
-/**
- * converts a int number into bytes with prefix in two decimals precision
- * currently precision is fixed, if dynamic needs check for max/min precision
- * @param  {Number|BigInt} bytes bytes in int
- * @return {String}       string in GB/MB/KB
- */
-function _formatBytes(bytes)
-{
-	var i = -1;
-	// If this ia bigint -> convert to number, we need the decimals
-	if (typeof bytes === "bigint") {
-		bytes = Number(bytes);
-	}
-	do {
-		bytes = bytes / 1024;
-		i++;
-	} while (bytes > 99);
-	return (
-		Math.round(bytes * Math.pow(10, 2)) / Math.pow(10, 2)
-	) + ['kB', 'MB', 'GB', 'TB', 'PB', 'EB'][i];
-}
-
 document.addEventListener('DOMContentLoaded', function() {
 	console.log('JavaScript Utils Test');
 	let el = document.getElementById('test-div');
@@ -52,10 +30,6 @@ document.addEventListener('DOMContentLoaded', function() {
 	el.innerHTML += '<div>formatBytes: ' + formatBytes(bytes) + '</div>';
 	el.innerHTML += '<div>formatBytesLong: ' + formatBytesLong(bytes) + '</div>';
 
-	// el.innerHTML += '<div>_formatBytes: ' + _formatBytes(1024n) + '</div>';
-	el.innerHTML += '<div>_formatBytes: ' + _formatBytes(1021152n) + '</div>';
-	el.innerHTML += '<div>_formatBytes: ' + _formatBytes(1021152) + '</div>';
-
 	// console.log('TR: %s', l10n.__('Original'));
 	// console.log('TR: %s', l10n.__('Not exists'));
 });
diff --git a/package.json b/package.json
index 4b5d2f7..1df2cf7 100644
--- a/package.json
+++ b/package.json
@@ -3,7 +3,8 @@
 	"version": "1.0.0",
 	"main": "",
 	"scripts": {
-		"test": "node test test/Test*.js",
+		"test": "vitest",
+		"coverage": "vitest run --coverage",
 		"utils-min-build": "node_modules/esbuild/bin/esbuild utils.min=src/utils.mjs --outdir=build/js/output/ --format=esm --bundle --charset=utf8 --tree-shaking=false --minify-whitespace --minify-syntax --sourcemap",
 		"utils-build": "node_modules/esbuild/bin/esbuild utils=src/utils.mjs --outdir=build/js/output/ --format=esm --bundle --charset=utf8 --tree-shaking=false",
 		"utils-build-all": "npm run utils-min-build && npm run utils-build",
diff --git a/src/utils/StringHelpers.mjs b/src/utils/StringHelpers.mjs
index e488ce3..b29fa75 100644
--- a/src/utils/StringHelpers.mjs
+++ b/src/utils/StringHelpers.mjs
@@ -8,7 +8,7 @@ export { formatString, numberWithCommas, convertLBtoBR };
 
 /**
  * simple sprintf formater for replace
- * usage: "{0} is cool, {1} is not".format("Alpha", "Beta");
+ * usage: formatString("{0} is cool, {1} is not", "Alpha", "Beta");
  * First, checks if it isn't implemented yet.
  * @param  {String} string String with {..} entries
  * @param  {...any} args   List of replacement
diff --git a/src/utils/UniqIdGenerators.mjs b/src/utils/UniqIdGenerators.mjs
index 0b51fb6..f31eeeb 100644
--- a/src/utils/UniqIdGenerators.mjs
+++ b/src/utils/UniqIdGenerators.mjs
@@ -25,7 +25,7 @@ function generateId(len)
 }
 
 /**
- * creates a pseudo random string of 10 characters
+ * creates a pseudo random string of 11 characters
  * works on all browsers
  * after many runs it will create duplicates
  * @return {String} not true random string
diff --git a/tests/StringHelpers.test.js b/tests/StringHelpers.test.js
new file mode 100644
index 0000000..e789837
--- /dev/null
+++ b/tests/StringHelpers.test.js
@@ -0,0 +1,60 @@
+import { describe, it, expect } from "vitest";
+
+import {
+	formatString,
+	numberWithCommas,
+	convertLBtoBR
+} from '../src/utils/StringHelpers.mjs';
+
+describe("formatString", () => {
+	it('Should replace {n} entries in strings', () => {
+		expect(
+			formatString("{0} is cool, {1} is not", "Alpha", "Beta")
+		).toBe("Alpha is cool, Beta is not");
+		expect(
+			formatString("{0} is cool, {1} is not", "Alpha")
+		).toBe("Alpha is cool, {1} is not");
+	});
+});
+
+describe("numberWithCommas", () => {
+	it('Should format a number into a decimal formatted', () => {
+		let numbers_list = [
+			{
+				"in": 123,
+				"out": "123",
+			},
+			{
+				"in": 1234,
+				"out": "1,234"
+			},
+			{
+				"in": 12345,
+				"out": "12,345"
+			},
+			{
+				"in": 123456,
+				"out": "123,456"
+			},
+			{
+				"in": 1234567,
+				"out": "1,234,567"
+			},
+			{
+				"in": 1234567890,
+				"out": "1,234,567,890"
+			},
+		];
+		for (let number of numbers_list) {
+			expect(numberWithCommas(number.in)).toBe(number.out);
+		}
+	});
+});
+
+describe("convertLBtoBR", () => {
+	it('Should convert LF/CR to <br>', () => {
+		expect(convertLBtoBR("AB\nCD")).toBe("AB<br>CD");
+	});
+});
+
+// __END__
diff --git a/tests/UniqIdGenerators.test.js b/tests/UniqIdGenerators.test.js
new file mode 100644
index 0000000..992f68b
--- /dev/null
+++ b/tests/UniqIdGenerators.test.js
@@ -0,0 +1,29 @@
+import { describe, it, expect } from "vitest";
+
+import {
+	// generateId,
+	randomIdF,
+} from '../src/utils/UniqIdGenerators.mjs';
+
+// window. is not defined in headless mode
+// TODO: fix
+/* describe("generateId", () => {
+	it('Should create a random id in defined length', () => {
+		let len_list = [
+			1, 12, 24, 32, 64
+		];
+		for (let len of len_list) {
+			expect(generateId(len)).lengthOf(len);
+		}
+	});
+}); */
+
+describe("randomIdF", () => {
+	it('Should create a 10 character long random id', () => {
+		let rand_id = randomIdF();
+		expect(rand_id).lengthOf(11);
+		expect(rand_id).match(/^[a-z0-9]{11}$/);
+	});
+});
+
+// __END__
diff --git a/tests/UrlParser.test.js b/tests/UrlParser.test.js
new file mode 100644
index 0000000..7242746
--- /dev/null
+++ b/tests/UrlParser.test.js
@@ -0,0 +1,22 @@
+import { describe, it, expect } from "vitest";
+
+import {
+	parseQueryString,
+	getQueryStringParam,
+} from '../src/utils/UrlParser.mjs';
+
+describe("parseQueryString", () => {
+	it('Should parse query string for key', () => {
+		let kv = parseQueryString("http://foor.org?key=value");
+		expect(kv).toEqual({"http://foor.org?key": "value"});
+	});
+});
+
+describe("getQueryStringParam", () => {
+	it('Should parse query string for key', () => {
+		let kv = getQueryStringParam("key", "http://foor.org?key=value");
+		expect(kv).toEqual("value");
+	});
+});
+
+// __END__