diff --git a/.prettierignore b/.prettierignore
new file mode 100644
index 000000000..71d07c514
--- /dev/null
+++ b/.prettierignore
@@ -0,0 +1 @@
+demos/*.html
\ No newline at end of file
diff --git a/.webpack/webpack.config.base.js b/.webpack/webpack.config.base.js
index 24db2a4f3..be56ce0ba 100644
--- a/.webpack/webpack.config.base.js
+++ b/.webpack/webpack.config.base.js
@@ -6,7 +6,7 @@ export default {
   amd: false, // https://github.com/lodash/lodash/issues/3052
   target: 'web',
   entry: {
-    mermaid: './src/mermaid.ts',
+    mermaid: './src/mermaid',
   },
   resolve: {
     extensions: ['.wasm', '.mjs', '.js', '.ts', '.json', '.jison'],
diff --git a/.webpack/webpack.config.e2e.babel.js b/.webpack/webpack.config.e2e.babel.js
index b9c5b7733..801460a71 100644
--- a/.webpack/webpack.config.e2e.babel.js
+++ b/.webpack/webpack.config.e2e.babel.js
@@ -4,7 +4,7 @@ import { merge } from 'webpack-merge';
 export default merge(baseConfig, {
   mode: 'development',
   entry: {
-    mermaid: './src/mermaid.ts',
+    mermaid: './src/mermaid',
     e2e: './cypress/platform/viewer.js',
     'bundle-test': './cypress/platform/bundle-test.js',
   },
diff --git a/package.json b/package.json
index 9aceb6568..899a07bcc 100644
--- a/package.json
+++ b/package.json
@@ -31,6 +31,7 @@
     "lint:fix": "yarn lint --fix",
     "e2e:depr": "yarn lint && jest e2e --config e2e/jest.config.js",
     "cypress": "cypress run",
+    "cypress:open": "cypress open",
     "e2e": "start-server-and-test dev http://localhost:9000/ cypress",
     "e2e-upd": "yarn lint && jest e2e -u --config e2e/jest.config.js",
     "dev": "webpack serve --config ./.webpack/webpack.config.e2e.babel.js",
@@ -129,4 +130,4 @@
     "**/*.css",
     "**/*.scss"
   ]
-}
+}
\ No newline at end of file
diff --git a/src/@types/config.d.ts b/src/@types/config.d.ts
index 2e947273d..9c63be1ac 100644
--- a/src/@types/config.d.ts
+++ b/src/@types/config.d.ts
@@ -8,6 +8,7 @@ export interface MermaidConfig {
   themeCSS?: string;
   maxTextSize?: number;
   darkMode?: boolean;
+  htmlLabels?: boolean;
   fontFamily?: string;
   logLevel?: number;
   securityLevel?: string;
diff --git a/src/config.js b/src/config.ts
similarity index 84%
rename from src/config.js
rename to src/config.ts
index 59c6c18cb..22804f988 100644
--- a/src/config.js
+++ b/src/config.ts
@@ -2,16 +2,17 @@ import assignWithDepth from './assignWithDepth';
 import { log } from './logger';
 import theme from './themes';
 import config from './defaultConfig';
+import { MermaidConfig } from 'types/config';
 
-export const defaultConfig = Object.freeze(config);
+export const defaultConfig: MermaidConfig = Object.freeze(config);
 
-let siteConfig = assignWithDepth({}, defaultConfig);
-let configFromInitialize;
-let directives = [];
-let currentConfig = assignWithDepth({}, defaultConfig);
+let siteConfig: MermaidConfig = assignWithDepth({}, defaultConfig);
+let configFromInitialize: MermaidConfig;
+let directives: any[] = [];
+let currentConfig: MermaidConfig = assignWithDepth({}, defaultConfig);
 
-export const updateCurrentConfig = (siteCfg, _directives) => {
-  // start with config beeing the siteConfig
+export const updateCurrentConfig = (siteCfg: MermaidConfig, _directives: any[]) => {
+  // start with config being the siteConfig
   let cfg = assignWithDepth({}, siteCfg);
   // let sCfg = assignWithDepth(defaultConfig, siteConfigDelta);
 
@@ -27,12 +28,15 @@ export const updateCurrentConfig = (siteCfg, _directives) => {
 
   cfg = assignWithDepth(cfg, sumOfDirectives);
 
+  // @ts-ignore
   if (sumOfDirectives.theme && theme[sumOfDirectives.theme]) {
     const tmpConfigFromInitialize = assignWithDepth({}, configFromInitialize);
     const themeVariables = assignWithDepth(
       tmpConfigFromInitialize.themeVariables || {},
+      // @ts-ignore
       sumOfDirectives.themeVariables
     );
+    // @ts-ignore
     cfg.themeVariables = theme[cfg.theme].getThemeVariables(themeVariables);
   }
 
@@ -55,11 +59,13 @@ export const updateCurrentConfig = (siteCfg, _directives) => {
  * @param conf - The base currentConfig to use as siteConfig
  * @returns {object} - The siteConfig
  */
-export const setSiteConfig = (conf) => {
+export const setSiteConfig = (conf: MermaidConfig): MermaidConfig => {
   siteConfig = assignWithDepth({}, defaultConfig);
   siteConfig = assignWithDepth(siteConfig, conf);
 
+  // @ts-ignore
   if (conf.theme && theme[conf.theme]) {
+    // @ts-ignore
     siteConfig.themeVariables = theme[conf.theme].getThemeVariables(conf.themeVariables);
   }
 
@@ -67,11 +73,11 @@ export const setSiteConfig = (conf) => {
   return siteConfig;
 };
 
-export const saveConfigFromInitialize = (conf) => {
+export const saveConfigFromInitialize = (conf: MermaidConfig): void => {
   configFromInitialize = assignWithDepth({}, conf);
 };
 
-export const updateSiteConfig = (conf) => {
+export const updateSiteConfig = (conf: MermaidConfig): MermaidConfig => {
   siteConfig = assignWithDepth(siteConfig, conf);
   updateCurrentConfig(siteConfig, directives);
 
@@ -88,7 +94,7 @@ export const updateSiteConfig = (conf) => {
  *
  * @returns {object} - The siteConfig
  */
-export const getSiteConfig = () => {
+export const getSiteConfig = (): MermaidConfig => {
   return assignWithDepth({}, siteConfig);
 };
 /**
@@ -105,7 +111,7 @@ export const getSiteConfig = () => {
  * @param {any} conf - The potential currentConfig
  * @returns {any} - The currentConfig merged with the sanitized conf
  */
-export const setConfig = (conf) => {
+export const setConfig = (conf: MermaidConfig): MermaidConfig => {
   // sanitize(conf);
   // Object.keys(conf).forEach(key => {
   //   const manipulator = manipulators[key];
@@ -143,17 +149,14 @@ export const getConfig = () => {
  *
  * @param {any} options - The potential setConfig parameter
  */
-export const sanitize = (options) => {
+export const sanitize = (options: any) => {
   // Checking that options are not in the list of excluded options
-  Object.keys(siteConfig.secure).forEach((key) => {
-    if (typeof options[siteConfig.secure[key]] !== 'undefined') {
-      // DO NOT attempt to print options[siteConfig.secure[key]] within `${}` as a malicious script
+  siteConfig.secure?.forEach((key) => {
+    if (typeof options[key] !== 'undefined') {
+      // DO NOT attempt to print options[key] within `${}` as a malicious script
       // can exploit the logger's attempt to stringify the value and execute arbitrary code
-      log.debug(
-        `Denied attempt to modify a secure key ${siteConfig.secure[key]}`,
-        options[siteConfig.secure[key]]
-      );
-      delete options[siteConfig.secure[key]];
+      log.debug(`Denied attempt to modify a secure key ${key}`, options[key]);
+      delete options[key];
     }
   });
 
@@ -186,7 +189,7 @@ export const sanitize = (options) => {
  *
  * @param {object} directive The directive to push in
  */
-export const addDirective = (directive) => {
+export const addDirective = (directive: any) => {
   if (directive.fontFamily) {
     if (!directive.themeVariables) {
       directive.themeVariables = { fontFamily: directive.fontFamily };
@@ -215,7 +218,7 @@ export const addDirective = (directive) => {
  *
  * **Notes**: (default: current siteConfig ) (optional, default `getSiteConfig()`)
  */
-export const reset = () => {
+export const reset = (): void => {
   // Replace current config with siteConfig
   directives = [];
   updateCurrentConfig(siteConfig, directives);
diff --git a/src/diagram-api/detectType.ts b/src/diagram-api/detectType.ts
index 3a3250aa0..3066c55c1 100644
--- a/src/diagram-api/detectType.ts
+++ b/src/diagram-api/detectType.ts
@@ -40,10 +40,10 @@ const diagramMatchers: Record<string, RegExp> = {
  *   class: { defaultRenderer: string } | undefined;
  *   state: { defaultRenderer: string } | undefined;
  *   flowchart: { defaultRenderer: string } | undefined;
- * }} [cnf]
+ * }} [config]
  * @returns {string} A graph definition key
  */
-export const detectType = function (text: string, cnf: MermaidConfig): string {
+export const detectType = function (text: string, config?: MermaidConfig): string {
   text = text.replace(directive, '').replace(anyComment, '\n');
   for (const [diagram, matcher] of Object.entries(diagramMatchers)) {
     if (text.match(matcher)) {
@@ -52,16 +52,16 @@ export const detectType = function (text: string, cnf: MermaidConfig): string {
   }
 
   if (text.match(/^\s*classDiagram/)) {
-    if (cnf?.class?.defaultRenderer === 'dagre-wrapper') return 'classDiagram';
+    if (config?.class?.defaultRenderer === 'dagre-wrapper') return 'classDiagram';
     return 'class';
   }
 
   if (text.match(/^\s*stateDiagram/)) {
-    if (cnf?.state?.defaultRenderer === 'dagre-wrapper') return 'stateDiagram';
+    if (config?.state?.defaultRenderer === 'dagre-wrapper') return 'stateDiagram';
     return 'state';
   }
 
-  if (cnf?.flowchart?.defaultRenderer === 'dagre-wrapper') {
+  if (config?.flowchart?.defaultRenderer === 'dagre-wrapper') {
     return 'flowchart-v2';
   }
 
diff --git a/src/mermaid.ts b/src/mermaid.ts
index 13b693b8c..8272a037a 100644
--- a/src/mermaid.ts
+++ b/src/mermaid.ts
@@ -1,9 +1,8 @@
-// TODO: Remove
-// @ts-nocheck
 /**
  * Web page integration module for the mermaid framework. It uses the mermaidAPI for mermaid
  * functionality and to render the diagrams to svg code.
  */
+import { MermaidConfig } from 'types/config';
 import { log } from './logger';
 import mermaidAPI from './mermaidAPI';
 import utils from './utils';
@@ -31,73 +30,73 @@ import utils from './utils';
  *
  * Renders the mermaid diagrams
  */
-const init = function (config: any, ...nodes: any[]) {
+const init = function (
+  config?: MermaidConfig,
+  nodes?: string | HTMLElement | NodeListOf<HTMLElement>,
+  callback?: Function
+) {
   try {
-    initThrowsErrors(config, nodes);
+    initThrowsErrors(config, nodes, callback);
   } catch (e) {
     log.warn('Syntax Error rendering');
+    // @ts-ignore
     log.warn(e.str);
-    if (this.parseError) {
-      this.parseError(e);
+    if (mermaid.parseError) {
+      // @ts-ignore
+      mermaid.parseError(e);
     }
   }
 };
 
-const initThrowsErrors = function (config: any, nodes: any[]) {
+const initThrowsErrors = function (
+  config?: MermaidConfig,
+  nodes?: string | HTMLElement | NodeListOf<HTMLElement>,
+  callback?: Function
+) {
   const conf = mermaidAPI.getConfig();
   // console.log('Starting rendering diagrams (init) - mermaid.init', conf);
   if (config) {
+    // @ts-ignore
     mermaid.sequenceConfig = config;
   }
 
   // if last argument is a function this is the callback function
-  let callback: (id: string) => void;
-  if (typeof nodes[nodes.length - 1] === 'function') {
-    callback = nodes[nodes.length - 1];
-    log.debug('Callback function found');
+
+  if (!callback && typeof conf?.mermaid?.callback === 'function') {
+    callback = conf.mermaid.callback;
+  }
+  log.debug(`${!callback ? 'No ' : ''}Callback function found`);
+  let nodesToProcess: NodeListOf<HTMLElement>;
+  if (typeof nodes === 'undefined') {
+    nodesToProcess = document.querySelectorAll('.mermaid');
+  } else if (typeof nodes === 'string') {
+    nodesToProcess = document.querySelectorAll(nodes);
+  } else if (nodes instanceof HTMLElement) {
+    nodesToProcess = new NodeList() as NodeListOf<HTMLElement>;
+    nodesToProcess[0] = nodes;
+  } else if (nodes instanceof NodeList) {
+    nodesToProcess = nodes;
   } else {
-    if (typeof conf.mermaid !== 'undefined') {
-      if (typeof conf.mermaid.callback === 'function') {
-        callback = conf.mermaid.callback;
-        log.debug('Callback function found');
-      } else {
-        log.debug('No Callback function found');
-      }
-    }
-  }
-  nodes =
-    nodes === undefined
-      ? document.querySelectorAll('.mermaid')
-      : typeof nodes === 'string'
-      ? document.querySelectorAll(nodes)
-      : nodes instanceof window.Node
-      ? [nodes]
-      : nodes; // Last case  - sequence config was passed pick next
-
-  log.debug('Start On Load before: ' + mermaid.startOnLoad);
-  if (typeof mermaid.startOnLoad !== 'undefined') {
-    log.debug('Start On Load inner: ' + mermaid.startOnLoad);
-    mermaidAPI.updateSiteConfig({ startOnLoad: mermaid.startOnLoad });
+    throw new Error('Invalid argument nodes for mermaid.init');
   }
 
-  if (typeof mermaid.ganttConfig !== 'undefined') {
-    mermaidAPI.updateSiteConfig({ gantt: mermaid.ganttConfig });
+  log.debug(`Found ${nodesToProcess.length} diagrams`);
+  if (typeof config?.startOnLoad !== 'undefined') {
+    log.debug('Start On Load: ' + config?.startOnLoad);
+    mermaidAPI.updateSiteConfig({ startOnLoad: config?.startOnLoad });
   }
 
   const idGenerator = new utils.initIdGenerator(conf.deterministicIds, conf.deterministicIDSeed);
 
   let txt;
 
-  for (let i = 0; i < nodes.length; i++) {
-    // element is the current div with mermaid class
-    const element = nodes[i];
-
+  // element is the current div with mermaid class
+  for (const element of Array.from(nodesToProcess)) {
     /*! Check if previously processed */
-    if (!element.getAttribute('data-processed')) {
-      element.setAttribute('data-processed', true);
-    } else {
+    if (element.getAttribute('data-processed')) {
       continue;
     }
+    element.setAttribute('data-processed', 'true');
 
     const id = `mermaid-${idGenerator.next()}`;
 
@@ -118,7 +117,7 @@ const initThrowsErrors = function (config: any, nodes: any[]) {
       mermaidAPI.render(
         id,
         txt,
-        (svgCode, bindFunctions) => {
+        (svgCode: string, bindFunctions: (el: HTMLElement) => void) => {
           element.innerHTML = svgCode;
           if (typeof callback !== 'undefined') {
             callback(id);
@@ -129,24 +128,15 @@ const initThrowsErrors = function (config: any, nodes: any[]) {
       );
     } catch (error) {
       log.warn('Catching Error (bootstrap)');
+      // @ts-ignore
+      // TODO: We should be throwing an error object.
       throw { error, message: error.str };
     }
   }
 };
 
-const initialize = function (config: any) {
-  // mermaidAPI.reset();
-  if (typeof config.mermaid !== 'undefined') {
-    if (typeof config.mermaid.startOnLoad !== 'undefined') {
-      mermaid.startOnLoad = config.mermaid.startOnLoad;
-    }
-    if (typeof config.mermaid.htmlLabels !== 'undefined') {
-      mermaid.htmlLabels =
-        config.mermaid.htmlLabels === 'false' || config.mermaid.htmlLabels === false ? false : true;
-    }
-  }
+const initialize = function (config: MermaidConfig) {
   mermaidAPI.initialize(config);
-  // mermaidAPI.reset();
 };
 
 /**
@@ -154,22 +144,9 @@ const initialize = function (config: any) {
  * configuration for mermaid rendering and calls init for rendering the mermaid diagrams on the page.
  */
 const contentLoaded = function () {
-  let config;
-
-  if (mermaid.startOnLoad) {
-    // No config found, do check API config
-    config = mermaidAPI.getConfig();
-    if (config.startOnLoad) {
-      mermaid.init();
-    }
-  } else {
-    if (typeof mermaid.startOnLoad === 'undefined') {
-      log.debug('In start, no config');
-      config = mermaidAPI.getConfig();
-      if (config.startOnLoad) {
-        mermaid.init();
-      }
-    }
+  const { startOnLoad } = mermaidAPI.getConfig();
+  if (startOnLoad) {
+    mermaid.init();
   }
 };
 
@@ -200,13 +177,12 @@ if (typeof document !== 'undefined') {
  *
  * @param {function (err, hash)} newParseErrorHandler New parseError() callback.
  */
-const setParseErrorHandler = function (newParseErrorHandler) {
+const setParseErrorHandler = function (newParseErrorHandler: (err: any, hash: any) => void) {
+  // @ts-ignore
   mermaid.parseError = newParseErrorHandler;
 };
 
 const mermaid = {
-  startOnLoad: true,
-  htmlLabels: true,
   diagrams: {},
   mermaidAPI,
   parse: mermaidAPI != undefined ? mermaidAPI.parse : null,
@@ -215,7 +191,7 @@ const mermaid = {
   init,
   initThrowsErrors,
   initialize,
-
+  parseError: undefined,
   contentLoaded,
 
   setParseErrorHandler,
diff --git a/src/utils.js b/src/utils.ts
similarity index 99%
rename from src/utils.js
rename to src/utils.ts
index 24fb965b5..d5f3b31a9 100644
--- a/src/utils.js
+++ b/src/utils.ts
@@ -1,3 +1,4 @@
+// @ts-nocheck
 import { sanitizeUrl } from '@braintree/sanitize-url';
 import {
   curveBasis,
@@ -18,6 +19,7 @@ import { configKeys } from './defaultConfig';
 import { log } from './logger';
 import { detectType } from './diagram-api/detectType';
 import assignWithDepth from './assignWithDepth';
+import { MermaidConfig } from 'types/config';
 
 // Effectively an enum of the supported curve types, accessible by name
 const d3CurveTypes = {
@@ -71,7 +73,7 @@ const anyComment = /\s*%%.*\n/gm;
  * @param {any} cnf
  * @returns {object} The json object representing the init passed to mermaid.initialize()
  */
-export const detectInit = function (text, cnf) {
+export const detectInit = function (text: string, config?: MermaidConfig): MermaidConfig {
   let inits = detectDirective(text, /(?:init\b)|(?:initialize\b)/);
   let results = {};
 
@@ -84,7 +86,7 @@ export const detectInit = function (text, cnf) {
     results = inits.args;
   }
   if (results) {
-    let type = detectType(text, cnf);
+    let type = detectType(text, config);
     ['config'].forEach((prop) => {
       if (typeof results[prop] !== 'undefined') {
         if (type === 'flowchart-v2') {