diff --git a/src/record/observer.ts b/src/record/observer.ts
index a3f1624b09..bfbf1a8a17 100644
--- a/src/record/observer.ts
+++ b/src/record/observer.ts
@@ -132,7 +132,9 @@ function initMoveObserver(
   const threshold =
     typeof sampling.mousemove === 'number' ? sampling.mousemove : 50;
   const callbackThreshold =
-    typeof sampling.mousemoveCallback === 'number' ? sampling.mousemoveCallback : 500;
+    typeof sampling.mousemoveCallback === 'number'
+      ? sampling.mousemoveCallback
+      : 500;
 
   let positions: mousePosition[] = [];
   let timeBaseline: number | null;
@@ -261,18 +263,18 @@ function initScrollObserver(
 function initViewportResizeObserver(
   cb: viewportResizeCallback,
 ): listenerHandler {
-  let last_h = -1;
-  let last_w = -1;
+  let lastH = -1;
+  let lastW = -1;
   const updateDimension = throttle(() => {
     const height = getWindowHeight();
     const width = getWindowWidth();
-    if (last_h !== height || last_w != width) {
+    if (lastH !== height || lastW !== width) {
       cb({
         width: Number(width),
         height: Number(height),
       });
-      last_h = height;
-      last_w = width;
+      lastH = height;
+      lastW = width;
     }
   }, 200);
   return on('resize', updateDimension, window);
@@ -562,24 +564,30 @@ function initLogObserver(
   logOptions: LogRecordOptions,
 ): listenerHandler {
   const logger = logOptions.logger;
-  if (!logger) return () => {};
+  if (!logger) {
+    return () => {};
+  }
   let logCount = 0;
-  const cancelHandlers: any[] = [];
+  const cancelHandlers: listenerHandler[] = [];
   // add listener to thrown errors
   if (logOptions.level!.includes('error')) {
     if (window) {
       const originalOnError = window.onerror;
+      // tslint:disable-next-line:no-any
       window.onerror = (...args: any[]) => {
-        originalOnError && originalOnError.apply(this, args);
-        let stack: Array<string> = [];
-        if (args[args.length - 1] instanceof Error)
+        if (originalOnError) {
+          originalOnError.apply(this, args);
+        }
+        let stack: string[] = [];
+        if (args[args.length - 1] instanceof Error) {
           // 0(the second parameter) tells parseStack that every stack in Error is useful
           stack = parseStack(args[args.length - 1].stack, 0);
+        }
         const payload = [stringify(args[0], logOptions.stringifyOptions)];
         cb({
           level: 'error',
           trace: stack,
-          payload: payload,
+          payload,
         });
       };
       cancelHandlers.push(() => {
@@ -587,8 +595,9 @@ function initLogObserver(
       });
     }
   }
-  for (const levelType of logOptions.level!)
+  for (const levelType of logOptions.level!) {
     cancelHandlers.push(replace(logger, levelType));
+  }
   return () => {
     cancelHandlers.forEach((h) => h());
   };
@@ -598,10 +607,13 @@ function initLogObserver(
    * @param logger the logger object such as Console
    * @param level the name of log function to be replaced
    */
-  function replace(logger: Logger, level: LogLevel) {
-    if (!logger[level]) return () => {};
+  function replace(_logger: Logger, level: LogLevel) {
+    if (!_logger[level]) {
+      return () => {};
+    }
     // replace the logger.{level}. return a restore function
-    return patch(logger, level, (original) => {
+    return patch(_logger, level, (original) => {
+      // tslint:disable-next-line:no-any
       return (...args: any[]) => {
         original.apply(this, args);
         try {
@@ -610,13 +622,13 @@ function initLogObserver(
             stringify(s, logOptions.stringifyOptions),
           );
           logCount++;
-          if (logCount < logOptions.lengthThreshold!)
+          if (logCount < logOptions.lengthThreshold!) {
             cb({
-              level: level,
+              level,
               trace: stack,
-              payload: payload,
+              payload,
             });
-          else if (logCount === logOptions.lengthThreshold)
+          } else if (logCount === logOptions.lengthThreshold) {
             // notify the user
             cb({
               level: 'warn',
@@ -625,6 +637,7 @@ function initLogObserver(
                 stringify('The number of log records reached the threshold.'),
               ],
             });
+          }
         } catch (error) {
           original('rrweb logger error:', error, ...args);
         }
@@ -639,7 +652,7 @@ function initLogObserver(
   function parseStack(
     stack: string | undefined,
     omitDepth: number = 1,
-  ): Array<string> {
+  ): string[] {
     let stacks: string[] = [];
     if (stack) {
       stacks = stack
diff --git a/src/record/stringify.ts b/src/record/stringify.ts
index 0547f2f32a..b1c69b81b9 100644
--- a/src/record/stringify.ts
+++ b/src/record/stringify.ts
@@ -1,3 +1,4 @@
+// tslint:disable:no-any no-bitwise forin
 /**
  * this file is used to serialize log message to string
  *
@@ -14,18 +15,21 @@ function pathToSelector(node: HTMLElement): string | '' {
     return '';
   }
 
-  var path = '';
+  let path = '';
   while (node.parentElement) {
-    var name = node.localName;
-    if (!name) break;
+    let name = node.localName;
+    if (!name) {
+      break;
+    }
     name = name.toLowerCase();
-    var parent = node.parentElement;
+    let parent = node.parentElement;
 
-    var domSiblings = [];
+    let domSiblings = [];
 
     if (parent.children && parent.children.length > 0) {
-      for (var i = 0; i < parent.children.length; i++) {
-        var sibling = parent.children[i];
+      // tslint:disable-next-line:prefer-for-of
+      for (let i = 0; i < parent.children.length; i++) {
+        let sibling = parent.children[i];
         if (sibling.localName && sibling.localName.toLowerCase) {
           if (sibling.localName.toLowerCase() === name) {
             domSiblings.push(sibling);
@@ -56,45 +60,55 @@ export function stringify(
     numOfKeysLimit: 50,
   };
   Object.assign(options, stringifyOptions);
-  let stack: any[] = [],
-    keys: any[] = [];
+  const stack: any[] = [];
+  const keys: any[] = [];
   return JSON.stringify(obj, function (key, value) {
     /**
      * forked from https://github.com/moll/json-stringify-safe/blob/master/stringify.js
      * to deCycle the object
      */
     if (stack.length > 0) {
-      var thisPos = stack.indexOf(this);
+      const thisPos = stack.indexOf(this);
       ~thisPos ? stack.splice(thisPos + 1) : stack.push(this);
       ~thisPos ? keys.splice(thisPos, Infinity, key) : keys.push(key);
       if (~stack.indexOf(value)) {
-        if (stack[0] === value) value = '[Circular ~]';
-        else
+        if (stack[0] === value) {
+          value = '[Circular ~]';
+        } else {
           value =
             '[Circular ~.' +
             keys.slice(0, stack.indexOf(value)).join('.') +
             ']';
+        }
       }
-    } else stack.push(value);
+    } else {
+      stack.push(value);
+    }
     /* END of the FORK */
 
-    if (value === null || value === undefined) return value;
+    if (value === null || value === undefined) {
+      return value;
+    }
     if (shouldToString(value)) {
       return toString(value);
     }
     if (value instanceof Event) {
       const eventResult: any = {};
-      for (const key in value) {
-        const eventValue = (value as any)[key];
-        if (Array.isArray(eventValue))
-          eventResult[key] = pathToSelector(
+      for (const eventKey in value) {
+        const eventValue = (value as any)[eventKey];
+        if (Array.isArray(eventValue)) {
+          eventResult[eventKey] = pathToSelector(
             eventValue.length ? eventValue[0] : null,
           );
-        else eventResult[key] = eventValue;
+        } else {
+          eventResult[eventKey] = eventValue;
+        }
       }
       return eventResult;
     } else if (value instanceof Node) {
-      if (value instanceof HTMLElement) return value ? value.outerHTML : '';
+      if (value instanceof HTMLElement) {
+        return value ? value.outerHTML : '';
+      }
       return value.nodeName;
     }
     return value;
@@ -103,21 +117,24 @@ export function stringify(
   /**
    * whether we should call toString function of this object
    */
-  function shouldToString(obj: object): boolean {
+  function shouldToString(_obj: object): boolean {
     if (
-      typeof obj === 'object' &&
-      Object.keys(obj).length > options.numOfKeysLimit
-    )
+      typeof _obj === 'object' &&
+      Object.keys(_obj).length > options.numOfKeysLimit
+    ) {
+      return true;
+    }
+    if (typeof _obj === 'function') {
       return true;
-    if (typeof obj === 'function') return true;
+    }
     return false;
   }
 
   /**
    * limit the toString() result according to option
    */
-  function toString(obj: object): string {
-    let str = obj.toString();
+  function toString(_obj: object): string {
+    let str = _obj.toString();
     if (options.stringLengthLimit && str.length > options.stringLengthLimit) {
       str = `${str.slice(0, options.stringLengthLimit)}...`;
     }
diff --git a/src/replay/index.ts b/src/replay/index.ts
index 1a79d5f982..719b17a677 100644
--- a/src/replay/index.ts
+++ b/src/replay/index.ts
@@ -52,7 +52,11 @@ const SKIP_TIME_INTERVAL = 5 * 1000;
 const mitt = (mittProxy as any).default || mittProxy;
 
 const REPLAY_CONSOLE_PREFIX = '[replayer]';
-const SCROLL_ATTRIBUTE_NAME = '__rrweb_scroll__';
+const ORIGINAL_ATTRIBUTE_NAME = '__rrweb_original__';
+
+type PatchedConsoleLog = {
+  [ORIGINAL_ATTRIBUTE_NAME]: typeof console.log;
+};
 
 const defaultMouseTailConfig = {
   duration: 500,
@@ -141,8 +145,9 @@ export class Replayer {
       logConfig: defaultLogConfig,
     };
     this.config = Object.assign({}, defaultConfig, config);
-    if (!this.config.logConfig.replayLogger)
+    if (!this.config.logConfig.replayLogger) {
       this.config.logConfig.replayLogger = this.getConsoleLogger();
+    }
 
     this.handleResize = this.handleResize.bind(this);
     this.getCastFn = this.getCastFn.bind(this);
@@ -1020,8 +1025,9 @@ export class Replayer {
         try {
           const logData = e.data as logData;
           const replayLogger = this.config.logConfig.replayLogger!;
-          if (typeof replayLogger[logData.level] === 'function')
+          if (typeof replayLogger[logData.level] === 'function') {
             replayLogger[logData.level]!(logData);
+          }
         } catch (error) {
           if (this.config.showWarning) {
             console.warn(error);
@@ -1319,7 +1325,9 @@ export class Replayer {
    * @param data the log data
    */
   private formatMessage(data: logData): string {
-    if (data.trace.length === 0) return '';
+    if (data.trace.length === 0) {
+      return '';
+    }
     const stackPrefix = '\n\tat ';
     let result = stackPrefix;
     result += data.trace.join(stackPrefix);
@@ -1330,29 +1338,38 @@ export class Replayer {
    * generate a console log replayer which implement the interface ReplayLogger
    */
   private getConsoleLogger(): ReplayLogger {
-    const rrwebOriginal = SCROLL_ATTRIBUTE_NAME;
     const replayLogger: ReplayLogger = {};
-    for (const level of this.config.logConfig.level!)
-      if (level === 'trace')
+    for (const level of this.config.logConfig.level!) {
+      if (level === 'trace') {
         replayLogger[level] = (data: logData) => {
-          const logger = (console.log as any)[rrwebOriginal]
-            ? (console.log as any)[rrwebOriginal]
+          const logger = ((console.log as unknown) as PatchedConsoleLog)[
+            ORIGINAL_ATTRIBUTE_NAME
+          ]
+            ? ((console.log as unknown) as PatchedConsoleLog)[
+                ORIGINAL_ATTRIBUTE_NAME
+              ]
             : console.log;
           logger(
             ...data.payload.map((s) => JSON.parse(s)),
             this.formatMessage(data),
           );
         };
-      else
+      } else {
         replayLogger[level] = (data: logData) => {
-          const logger = (console[level] as any)[rrwebOriginal]
-            ? (console[level] as any)[rrwebOriginal]
+          const logger = ((console[level] as unknown) as PatchedConsoleLog)[
+            ORIGINAL_ATTRIBUTE_NAME
+          ]
+            ? ((console[level] as unknown) as PatchedConsoleLog)[
+                ORIGINAL_ATTRIBUTE_NAME
+              ]
             : console[level];
           logger(
             ...data.payload.map((s) => JSON.parse(s)),
             this.formatMessage(data),
           );
         };
+      }
+    }
     return replayLogger;
   }
 
diff --git a/src/types.ts b/src/types.ts
index e9fa13d689..432e29a682 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -401,25 +401,25 @@ export type LogLevel =
 /* fork from interface Console */
 // all kinds of console functions
 export type Logger = {
-  assert?: (value: any, message?: string, ...optionalParams: any[]) => void;
-  clear?: () => void;
-  count?: (label?: string) => void;
-  countReset?: (label?: string) => void;
-  debug?: (message?: any, ...optionalParams: any[]) => void;
-  dir?: (obj: any, options?: NodeJS.InspectOptions) => void;
-  dirxml?: (...data: any[]) => void;
-  error?: (message?: any, ...optionalParams: any[]) => void;
-  group?: (...label: any[]) => void;
-  groupCollapsed?: (label?: any[]) => void;
+  assert?: typeof console.assert;
+  clear?: typeof console.clear;
+  count?: typeof console.count;
+  countReset?: typeof console.countReset;
+  debug?: typeof console.debug;
+  dir?: typeof console.dir;
+  dirxml?: typeof console.dirxml;
+  error?: typeof console.error;
+  group?: typeof console.group;
+  groupCollapsed?: typeof console.groupCollapsed;
   groupEnd?: () => void;
-  info?: (message?: any, ...optionalParams: any[]) => void;
-  log?: (message?: any, ...optionalParams: any[]) => void;
-  table?: (tabularData: any, properties?: ReadonlyArray<string>) => void;
-  time?: (label?: string) => void;
-  timeEnd?: (label?: string) => void;
-  timeLog?: (label?: string, ...data: any[]) => void;
-  trace?: (message?: any, ...optionalParams: any[]) => void;
-  warn?: (message?: any, ...optionalParams: any[]) => void;
+  info?: typeof console.info;
+  log?: typeof console.log;
+  table?: typeof console.table;
+  time?: typeof console.time;
+  timeEnd?: typeof console.timeEnd;
+  timeLog?: typeof console.timeLog;
+  trace?: typeof console.trace;
+  warn?: typeof console.warn;
 };
 
 /**
@@ -430,8 +430,8 @@ export type ReplayLogger = Partial<Record<LogLevel, (data: logData) => void>>;
 
 export type LogParam = {
   level: LogLevel;
-  trace: Array<string>;
-  payload: Array<string>;
+  trace: string[];
+  payload: string[];
 };
 
 export type fontCallback = (p: fontParam) => void;
@@ -511,7 +511,7 @@ export type playerConfig = {
 };
 
 export type LogReplayConfig = {
-  level?: Array<LogLevel> | undefined;
+  level?: LogLevel[] | undefined;
   replayLogger: ReplayLogger | undefined;
 };
 
@@ -583,7 +583,7 @@ export type StringifyOptions = {
 };
 
 export type LogRecordOptions = {
-  level?: Array<LogLevel> | undefined;
+  level?: LogLevel[] | undefined;
   lengthThreshold?: number;
   stringifyOptions?: StringifyOptions;
   logger?: Logger;