diff --git a/components/_util/isNumeric.ts b/components/_util/isNumeric.ts
deleted file mode 100644
index b1aeed28f1..0000000000
--- a/components/_util/isNumeric.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-const isNumeric = (value: any): boolean => !isNaN(parseFloat(value)) && isFinite(value);
-
-export default isNumeric;
diff --git a/components/layout/Sider.tsx b/components/layout/Sider.tsx
index 504854bc4b..71b0e9a69a 100644
--- a/components/layout/Sider.tsx
+++ b/components/layout/Sider.tsx
@@ -6,7 +6,6 @@ import RightOutlined from '@ant-design/icons/RightOutlined';
 import classNames from 'classnames';
 import omit from 'rc-util/lib/omit';
 
-import isNumeric from '../_util/isNumeric';
 import { ConfigContext } from '../config-provider';
 import { LayoutContext } from './context';
 import useStyle from './style/sider';
@@ -20,6 +19,8 @@ const dimensionMaxMap = {
   xxl: '1599.98px',
 };
 
+const isNumeric = (value: any) => !Number.isNaN(Number.parseFloat(value)) && isFinite(value);
+
 export interface SiderContextProps {
   siderCollapsed?: boolean;
 }
@@ -152,74 +153,77 @@ const Sider = React.forwardRef<HTMLDivElement, SiderProps>((props, ref) => {
     handleSetCollapsed(!collapsed, 'clickTrigger');
   };
 
-  const renderSider = () => {
-    const divProps = omit(otherProps, ['collapsed']);
-    const rawWidth = collapsed ? collapsedWidth : width;
-    // use "px" as fallback unit for width
-    const siderWidth = isNumeric(rawWidth) ? `${rawWidth}px` : String(rawWidth);
-    // special trigger when collapsedWidth == 0
-    const zeroWidthTrigger =
-      parseFloat(String(collapsedWidth || 0)) === 0 ? (
-        <span
-          onClick={toggle}
-          className={classNames(
-            `${prefixCls}-zero-width-trigger`,
-            `${prefixCls}-zero-width-trigger-${reverseArrow ? 'right' : 'left'}`,
-          )}
-          style={zeroWidthTriggerStyle}
-        >
-          {trigger || <BarsOutlined />}
-        </span>
-      ) : null;
-    const reverseIcon = (direction === 'rtl') === !reverseArrow;
-    const iconObj = {
-      expanded: reverseIcon ? <RightOutlined /> : <LeftOutlined />,
-      collapsed: reverseIcon ? <LeftOutlined /> : <RightOutlined />,
-    };
-    const status = collapsed ? 'collapsed' : 'expanded';
-    const defaultTrigger = iconObj[status];
-    const triggerDom =
-      trigger !== null
-        ? zeroWidthTrigger || (
-            <div className={`${prefixCls}-trigger`} onClick={toggle} style={{ width: siderWidth }}>
-              {trigger || defaultTrigger}
-            </div>
-          )
-        : null;
-
-    const divStyle: React.CSSProperties = {
-      ...style,
-      flex: `0 0 ${siderWidth}`,
-      maxWidth: siderWidth, // Fix width transition bug in IE11
-      minWidth: siderWidth, // https://github.com/ant-design/ant-design/issues/6349
-      width: siderWidth,
-    };
+  const divProps = omit(otherProps, ['collapsed']);
+  const rawWidth = collapsed ? collapsedWidth : width;
+  // use "px" as fallback unit for width
+  const siderWidth = isNumeric(rawWidth) ? `${rawWidth}px` : String(rawWidth);
+  // special trigger when collapsedWidth == 0
+  const zeroWidthTrigger =
+    parseFloat(String(collapsedWidth || 0)) === 0 ? (
+      <span
+        onClick={toggle}
+        className={classNames(
+          `${prefixCls}-zero-width-trigger`,
+          `${prefixCls}-zero-width-trigger-${reverseArrow ? 'right' : 'left'}`,
+        )}
+        style={zeroWidthTriggerStyle}
+      >
+        {trigger || <BarsOutlined />}
+      </span>
+    ) : null;
+
+  const reverseIcon = (direction === 'rtl') === !reverseArrow;
+
+  const iconObj = {
+    expanded: reverseIcon ? <RightOutlined /> : <LeftOutlined />,
+    collapsed: reverseIcon ? <LeftOutlined /> : <RightOutlined />,
+  };
 
-    const siderCls = classNames(
-      prefixCls,
-      `${prefixCls}-${theme}`,
-      {
-        [`${prefixCls}-collapsed`]: !!collapsed,
-        [`${prefixCls}-has-trigger`]: collapsible && trigger !== null && !zeroWidthTrigger,
-        [`${prefixCls}-below`]: !!below,
-        [`${prefixCls}-zero-width`]: parseFloat(siderWidth) === 0,
-      },
-      className,
-      hashId,
-      cssVarCls,
-    );
-    return (
-      <aside className={siderCls} {...divProps} style={divStyle} ref={ref}>
-        <div className={`${prefixCls}-children`}>{children}</div>
-        {collapsible || (below && zeroWidthTrigger) ? triggerDom : null}
-      </aside>
-    );
+  const status = collapsed ? 'collapsed' : 'expanded';
+  const defaultTrigger = iconObj[status];
+  const triggerDom =
+    trigger !== null
+      ? zeroWidthTrigger || (
+          <div className={`${prefixCls}-trigger`} onClick={toggle} style={{ width: siderWidth }}>
+            {trigger || defaultTrigger}
+          </div>
+        )
+      : null;
+
+  const divStyle: React.CSSProperties = {
+    ...style,
+    flex: `0 0 ${siderWidth}`,
+    maxWidth: siderWidth, // Fix width transition bug in IE11
+    minWidth: siderWidth, // https://github.com/ant-design/ant-design/issues/6349
+    width: siderWidth,
   };
 
-  const contextValue = React.useMemo(() => ({ siderCollapsed: collapsed }), [collapsed]);
+  const siderCls = classNames(
+    prefixCls,
+    `${prefixCls}-${theme}`,
+    {
+      [`${prefixCls}-collapsed`]: !!collapsed,
+      [`${prefixCls}-has-trigger`]: collapsible && trigger !== null && !zeroWidthTrigger,
+      [`${prefixCls}-below`]: !!below,
+      [`${prefixCls}-zero-width`]: parseFloat(siderWidth) === 0,
+    },
+    className,
+    hashId,
+    cssVarCls,
+  );
+
+  const contextValue = React.useMemo<SiderContextProps>(
+    () => ({ siderCollapsed: collapsed }),
+    [collapsed],
+  );
 
   return wrapCSSVar(
-    <SiderContext.Provider value={contextValue}>{renderSider()}</SiderContext.Provider>,
+    <SiderContext.Provider value={contextValue}>
+      <aside className={siderCls} {...divProps} style={divStyle} ref={ref}>
+        <div className={`${prefixCls}-children`}>{children}</div>
+        {collapsible || (below && zeroWidthTrigger) ? triggerDom : null}
+      </aside>
+    </SiderContext.Provider>,
   );
 });
 
diff --git a/docs/react/server-side-rendering.en-US.md b/docs/react/server-side-rendering.en-US.md
index f15c28c048..cc315e415e 100644
--- a/docs/react/server-side-rendering.en-US.md
+++ b/docs/react/server-side-rendering.en-US.md
@@ -243,16 +243,15 @@ import path from 'path';
 import { extractStyle } from '@ant-design/cssinjs';
 import type Entity from '@ant-design/cssinjs/lib/Cache';
 
-export type DoExtraStyleOptions = {
+export interface DoExtraStyleOptions {
   cache: Entity;
   dir?: string;
   baseFileName?: string;
-};
-export function doExtraStyle({
-  cache,
-  dir = 'antd-output',
-  baseFileName = 'antd.min',
-}: DoExtraStyleOptions) {
+}
+
+export const doExtraStyle = (opts: DoExtraStyleOptions) => {
+  const { cache, dir = 'antd-output', baseFileName = 'antd.min' } = opts;
+
   const baseDir = path.resolve(__dirname, '../../static/css');
 
   const outputCssPath = path.join(baseDir, dir);
@@ -262,7 +261,10 @@ export function doExtraStyle({
   }
 
   const css = extractStyle(cache, true);
-  if (!css) return '';
+
+  if (!css) {
+    return '';
+  }
 
   const md5 = createHash('md5');
   const hash = md5.update(css).digest('hex');
@@ -271,12 +273,14 @@ export function doExtraStyle({
 
   const res = `_next/static/css/${dir}/${fileName}`;
 
-  if (fs.existsSync(fullpath)) return res;
+  if (fs.existsSync(fullpath)) {
+    return res;
+  }
 
   fs.writeFileSync(fullpath, css);
 
   return res;
-}
+};
 ```
 
 Export on demand using the above tools in `_document.tsx`
diff --git a/docs/react/server-side-rendering.zh-CN.md b/docs/react/server-side-rendering.zh-CN.md
index 41869c6965..6c38da1afb 100644
--- a/docs/react/server-side-rendering.zh-CN.md
+++ b/docs/react/server-side-rendering.zh-CN.md
@@ -243,16 +243,15 @@ import path from 'path';
 import { extractStyle } from '@ant-design/cssinjs';
 import type Entity from '@ant-design/cssinjs/lib/Cache';
 
-export type DoExtraStyleOptions = {
+export interface DoExtraStyleOptions {
   cache: Entity;
   dir?: string;
   baseFileName?: string;
-};
-export function doExtraStyle({
-  cache,
-  dir = 'antd-output',
-  baseFileName = 'antd.min',
-}: DoExtraStyleOptions) {
+}
+
+export const doExtraStyle = (opts: DoExtraStyleOptions) => {
+  const { cache, dir = 'antd-output', baseFileName = 'antd.min' } = opts;
+
   const baseDir = path.resolve(__dirname, '../../static/css');
 
   const outputCssPath = path.join(baseDir, dir);
@@ -262,7 +261,10 @@ export function doExtraStyle({
   }
 
   const css = extractStyle(cache, true);
-  if (!css) return '';
+
+  if (!css) {
+    return '';
+  }
 
   const md5 = createHash('md5');
   const hash = md5.update(css).digest('hex');
@@ -271,12 +273,14 @@ export function doExtraStyle({
 
   const res = `_next/static/css/${dir}/${fileName}`;
 
-  if (fs.existsSync(fullpath)) return res;
+  if (fs.existsSync(fullpath)) {
+    return res;
+  }
 
   fs.writeFileSync(fullpath, css);
 
   return res;
-}
+};
 ```
 
 在 `_document.tsx` 中使用上述工具进行按需导出：