diff --git a/karma.conf.js b/karma.conf.js
index 3ff26d5..f70d0fc 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -1,16 +1,17 @@
-// const path = require('path')
-
 module.exports = function (config) {
   config.set({
-    frameworks: ['jasmine'],
+
+    frameworks: ['jasmine', 'karma-typescript'],
+
     files: [
-      'test/**/*.spec.js'
+      { pattern: 'test/**/*.ts' },
+      { pattern: 'src/**/*.ts' }
     ],
-    exclude: [],
+
     preprocessors: {
-      'test/**/*.js': ['webpack', 'sourcemap', 'coverage']
+      '**/*.ts': ['karma-typescript', 'sourcemap', 'coverage']
     },
-    reporters: ['progress', 'coverage'],
+    reporters: ['dots', 'coverage', 'karma-typescript'],
     coverageReporter: {
       dir: 'coverage/',
       type: 'lcov',
diff --git a/package.json b/package.json
index 225fb7d..fedd147 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,11 @@
   "repository": "https://github.com/crabbly/Print.js",
   "license": "MIT",
   "devDependencies": {
+    "@types/jasmine": "^3.4.0",
+    "karma": "^6.1.0",
+    "karma-cli": "^2.0.0",
+    "karma-typescript": "^5.5.3",
+    "typescript": "^5.0.2",
     "@babel/core": "7.11.6",
     "@babel/preset-env": "7.11.5",
     "babel-loader": "8.1.0",
@@ -15,7 +20,6 @@
     "css-loader": "4.2.2",
     "istanbul-instrumenter-loader": "3.0.1",
     "jasmine-core": "3.6.0",
-    "karma": "5.2.1",
     "karma-chrome-launcher": "3.1.0",
     "karma-coverage": "2.0.3",
     "karma-jasmine": "4.0.1",
@@ -28,8 +32,10 @@
     "sass-loader": "10.0.2",
     "standard": "14.3.4",
     "terser-webpack-plugin": "4.1.0",
+    "ts-loader": "^9.4.2",
     "webpack": "4.44.1",
     "webpack-cli": "3.3.12",
+    "source-map-loader": "^4.0.1",
     "webpack-dev-server": "3.11.0"
   },
   "scripts": {
diff --git a/src/index.js b/src/index.ts
similarity index 100%
rename from src/index.js
rename to src/index.ts
diff --git a/src/js/browser.js b/src/js/browser.ts
similarity index 95%
rename from src/js/browser.js
rename to src/js/browser.ts
index f600929..8aef10c 100644
--- a/src/js/browser.js
+++ b/src/js/browser.ts
@@ -3,7 +3,7 @@ const Browser = {
   isFirefox: () => {
     return typeof InstallTrigger !== 'undefined'
   },
-  getFirefoxMajorVersion: (userAgent) => {
+  getFirefoxMajorVersion: (userAgent = null) => {
     userAgent = userAgent || navigator.userAgent
     const firefoxVersionRegex = /firefox\/(\S+)/
     const match = userAgent.toLowerCase().match(firefoxVersionRegex)
diff --git a/src/js/functions.js b/src/js/functions.ts
similarity index 95%
rename from src/js/functions.js
rename to src/js/functions.ts
index e8548f4..ed70c3f 100644
--- a/src/js/functions.js
+++ b/src/js/functions.ts
@@ -64,17 +64,17 @@ export function addHeader (printElement, params) {
 
 export function addFooter (printElement, params) {
   // Create the footer container div
-  let footerContainer = document.createElement('div')
+  const footerContainer = document.createElement('div')
 
   // Check if the footer is text or raw html
   if (isRawHTML(params.footer)) {
     footerContainer.innerHTML = params.footer
   } else {
     // Create footer element
-    let footerElement = document.createElement('h1')
+    const footerElement = document.createElement('h1')
 
     // Create footer text node
-    let footerNode = document.createTextNode(params.footer)
+    const footerNode = document.createTextNode(params.footer)
 
     // Build and style
     footerElement.appendChild(footerNode)
diff --git a/src/js/html.js b/src/js/html.ts
similarity index 100%
rename from src/js/html.js
rename to src/js/html.ts
diff --git a/src/js/image.js b/src/js/image.ts
similarity index 100%
rename from src/js/image.js
rename to src/js/image.ts
diff --git a/src/js/init.js b/src/js/init.ts
similarity index 92%
rename from src/js/init.js
rename to src/js/init.ts
index 8d2515e..5eedb75 100644
--- a/src/js/init.js
+++ b/src/js/init.ts
@@ -84,7 +84,7 @@ export default {
     if (!params.printable) throw new Error('Missing printable information.')
 
     // Validate type
-    if (!params.type || typeof params.type !== 'string' || printTypes.indexOf(params.type.toLowerCase()) === -1) {
+    if (!params.type || (typeof params.type !== 'string') || printTypes.indexOf(params.type.toLowerCase()) === -1) {
       throw new Error('Invalid print type. Available types are: pdf, html, image and json.')
     }
 
@@ -97,7 +97,9 @@ export default {
     // To prevent duplication and issues, remove any used printFrame from the DOM
     const usedFrame = document.getElementById(params.frameId)
 
-    if (usedFrame) usedFrame.parentNode.removeChild(usedFrame)
+    if (usedFrame) {
+      usedFrame.parentNode.removeChild(usedFrame)
+    }
 
     // Create a new iframe for the print job
     const printFrame = document.createElement('iframe')
@@ -122,7 +124,9 @@ export default {
       // Attach css files
       if (params.css) {
         // Add support for single file
-        if (!Array.isArray(params.css)) params.css = [params.css]
+        if (!Array.isArray(params.css)) {
+          params.css = [params.css]
+        }
 
         // Create link tags for each css file
         params.css.forEach(file => {
@@ -147,8 +151,12 @@ export default {
             params.onError(error)
           } finally {
             // Make sure there is no loading modal opened
-            if (params.showModal) Modal.close()
-            if (params.onLoadingEnd) params.onLoadingEnd()
+            if (params.showModal) {
+              Modal.close()
+            }
+            if (params.onLoadingEnd) {
+              params.onLoadingEnd()
+            }
           }
         } else {
           Pdf.print(params, printFrame)
diff --git a/src/js/json.js b/src/js/json.ts
similarity index 100%
rename from src/js/json.js
rename to src/js/json.ts
diff --git a/src/js/modal.js b/src/js/modal.ts
similarity index 100%
rename from src/js/modal.js
rename to src/js/modal.ts
diff --git a/src/js/pdf.js b/src/js/pdf.ts
similarity index 80%
rename from src/js/pdf.js
rename to src/js/pdf.ts
index 9dc420b..24e5b9f 100644
--- a/src/js/pdf.js
+++ b/src/js/pdf.ts
@@ -5,10 +5,10 @@ export default {
   print: (params, printFrame) => {
     // Check if we have base64 data
     if (params.base64) {
-        if (params.printable.indexOf(',') !== -1) {
-            //If pdf base64 start with `data:application/pdf;base64,`,Excute the atob function will throw an error.So we get the content after `,`
-            params.printable = params.printable.split(',')[1];
-        }
+      if (params.printable.indexOf(',') !== -1) {
+        // If pdf base64 start with `data:application/pdf;base64,`,Excute the atob function will throw an error.So we get the content after `,`
+        params.printable = params.printable.split(',')[1]
+      }
       const bytesArray = Uint8Array.from(atob(params.printable), c => c.charCodeAt(0))
       createBlobAndPrint(params, printFrame, bytesArray)
       return
@@ -51,8 +51,7 @@ export default {
 
 function createBlobAndPrint (params, printFrame, data) {
   // Pass response or base64 data to a blob and create a local object url
-  let localPdf = new window.Blob([data], { type: 'application/pdf' })
-  localPdf = window.URL.createObjectURL(localPdf)
+  let localPdf = window.URL.createObjectURL(new window.Blob([data], { type: 'application/pdf' }))
 
   // Set iframe src with pdf document url
   printFrame.setAttribute('src', localPdf)
diff --git a/src/js/print.js b/src/js/print.ts
similarity index 93%
rename from src/js/print.js
rename to src/js/print.ts
index 40f9629..df27e0d 100644
--- a/src/js/print.js
+++ b/src/js/print.ts
@@ -59,15 +59,15 @@ function performPrint (iframeElement, params) {
       try {
         iframeElement.contentWindow.document.execCommand('print', false, null)
       } catch (e) {
-        setTimeout(function(){
+        setTimeout(function () {
           iframeElement.contentWindow.print()
-        },1000)
+        }, 1000)
       }
     } else {
       // Other browsers
-      setTimeout(function(){
+      setTimeout(function () {
         iframeElement.contentWindow.print()
-      },1000)
+      }, 1000)
     }
   } catch (error) {
     params.onError(error)
@@ -82,7 +82,7 @@ function performPrint (iframeElement, params) {
   }
 }
 
-function loadIframeImages (images) {
+function loadIframeImages (images){
   const promises = images.map(image => {
     if (image.src && image.src !== window.location.href) {
       return loadIframeImage(image)
@@ -93,11 +93,11 @@ function loadIframeImages (images) {
 }
 
 function loadIframeImage (image) {
-  return new Promise(resolve => {
+  return new Promise (resolve => {
     const pollImage = () => {
       !image || typeof image.naturalWidth === 'undefined' || image.naturalWidth === 0 || !image.complete
         ? setTimeout(pollImage, 500)
-        : resolve()
+        : resolve(true)
     }
     pollImage()
   })
diff --git a/src/js/raw-html.js b/src/js/raw-html.ts
similarity index 100%
rename from src/js/raw-html.js
rename to src/js/raw-html.ts
diff --git a/src/js/types/browser.d.ts b/src/js/types/browser.d.ts
new file mode 100644
index 0000000..dd32988
--- /dev/null
+++ b/src/js/types/browser.d.ts
@@ -0,0 +1 @@
+declare const InstallTrigger: any;
\ No newline at end of file
diff --git a/src/index.d.ts b/src/js/types/index.d.ts
similarity index 84%
rename from src/index.d.ts
rename to src/js/types/index.d.ts
index 5c5d325..fcc27ff 100644
--- a/src/index.d.ts
+++ b/src/js/types/index.d.ts
@@ -1,6 +1,24 @@
+export {}
+
 declare function printJS(configuration: printJS.Configuration): void;
 declare function printJS(source: string, type?: printJS.PrintTypes): void;
 
+declare global {
+  interface Window {
+    printJS: Function;
+    StyleMedia: any;
+    chrome: any;
+  }
+
+  interface Document {
+    documentMode: any;
+  }
+
+  interface HTMLElement {
+    contentWindow: any;
+    contentDocument: any;
+  }
+}
 declare namespace printJS {
   type PrintTypes = 'pdf' | 'html' | 'image' | 'json' | 'raw-html';
 
@@ -43,6 +61,4 @@ declare namespace printJS {
     honorColor?: boolean;
     imageStyle?: string;
   }
-}
-
-export = printJS;
+}
\ No newline at end of file
diff --git a/test/unit/browser.spec.js b/test/unit/browser.spec.ts
similarity index 93%
rename from test/unit/browser.spec.js
rename to test/unit/browser.spec.ts
index 342a576..bacbeb6 100644
--- a/test/unit/browser.spec.js
+++ b/test/unit/browser.spec.ts
@@ -35,12 +35,12 @@ describe('Browser', () => {
 
   describe('isChrome()', () => {
     it('returns true for Google Chrome', () => {
-      const stubbedWindow = { chrome: {} }
+      const stubbedWindow = <Window & typeof globalThis> { chrome: {} }
       expect(Browser.isChrome(stubbedWindow)).toBeTruthy()
     })
 
     it('returns false for non Google Chrome', () => {
-      const stubbedWindow = {}
+      const stubbedWindow = <Window & typeof globalThis> {}
       expect(Browser.isChrome(stubbedWindow)).toBeFalsy()
     })
   })
diff --git a/test/unit/functions.spec.js b/test/unit/functions.spec.ts
similarity index 100%
rename from test/unit/functions.spec.js
rename to test/unit/functions.spec.ts
diff --git a/test/unit/html.spec.js b/test/unit/html.spec.ts
similarity index 100%
rename from test/unit/html.spec.js
rename to test/unit/html.spec.ts
diff --git a/test/unit/image.spec.js b/test/unit/image.spec.ts
similarity index 100%
rename from test/unit/image.spec.js
rename to test/unit/image.spec.ts
diff --git a/test/unit/init.spec.js b/test/unit/init.spec.ts
similarity index 100%
rename from test/unit/init.spec.js
rename to test/unit/init.spec.ts
diff --git a/test/unit/json.spec.js b/test/unit/json.spec.ts
similarity index 100%
rename from test/unit/json.spec.js
rename to test/unit/json.spec.ts
diff --git a/test/unit/modal.spec.js b/test/unit/modal.spec.ts
similarity index 100%
rename from test/unit/modal.spec.js
rename to test/unit/modal.spec.ts
diff --git a/test/unit/pdf.spec.js b/test/unit/pdf.spec.ts
similarity index 100%
rename from test/unit/pdf.spec.js
rename to test/unit/pdf.spec.ts
diff --git a/test/unit/print.spec.js b/test/unit/print.spec.ts
similarity index 100%
rename from test/unit/print.spec.js
rename to test/unit/print.spec.ts
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..5602ac8
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,40 @@
+{
+  "compileOnSave": false,
+  "compilerOptions": {
+    "module": "esnext",
+    "strict": true,
+    "noImplicitAny": false,
+    "outDir": "tmp",
+    "moduleResolution": "node",
+    "esModuleInterop": true,
+    "experimentalDecorators": true,
+    "target": "es5",
+    "sourceMap": true,
+    "baseUrl": ".",
+    "allowSyntheticDefaultImports": true,
+    "types" : [
+      "jasmine",
+      "node"
+    ],
+    "typeRoots": ["./node_modules/@types", "./src/js/types"],
+    "paths": {
+      "@/*": [
+        "src/*"
+      ]
+    },
+    "lib": [
+      "esnext",
+      "dom",
+      "dom.iterable",
+      "scripthost"
+    ]
+
+  },
+  "include": [
+    "src/**/*.ts",
+    "test/**/*.ts"
+  ],
+  "exclude": [
+    "node_modules"
+  ]
+}
diff --git a/webpack.config.js b/webpack.config.js
index a719b37..41eae9a 100644
--- a/webpack.config.js
+++ b/webpack.config.js
@@ -7,8 +7,11 @@ module.exports = {
   mode: 'development',
   devtool: 'source-map',
   entry: [
-    './src/index.js'
+    './src/index.ts'
   ],
+  resolve: {
+    extensions: ['.ts', '.js', '.json']
+  },
   output: {
     library: 'printJS',
     libraryTarget: 'umd',
@@ -23,7 +26,7 @@ module.exports = {
         test: /\.js$/,
         exclude: /node_modules/,
         use: {
-          loader: 'babel-loader'
+          loader: 'ts-loader'
         }
       },
       // TODO: Configure istanbul to interpret how webpack bundles files