refactor: improve heading styles implementation

- Extract defaultHeadingConfig constant to reduce duplication
- Fix headingConfig parameter default value consistency
- Simplify styles generation with single utility function
- Add TypeScript definitions for heading configuration
- Fix spacing logic to use !== undefined checks

Author: DemoMacro

index.d.ts

@@ -36,6 +36,30 @@ declare namespace HTMLtoDOCX {
         restart: "continuous" | "newPage" | "newSection";
     }
 
+    interface HeadingSpacing {
+        before?: number;
+        after?: number;
+    }
+
+    interface HeadingStyle {
+        font?: string | null;
+        fontSize?: number | null;
+        bold?: boolean;
+        spacing?: HeadingSpacing;
+        keepLines?: boolean;
+        keepNext?: boolean;
+        outlineLevel?: number;
+    }
+
+    interface HeadingConfig {
+        heading1?: HeadingStyle;
+        heading2?: HeadingStyle;
+        heading3?: HeadingStyle;
+        heading4?: HeadingStyle;
+        heading5?: HeadingStyle;
+        heading6?: HeadingStyle;
+    }
+
     interface DocumentOptions {
         orientation?: "portrait" | "landscape";
         pageSize?: PageSize;
@@ -64,6 +88,7 @@ declare namespace HTMLtoDOCX {
         numbering?: {
             defaultOrderedListStyleType?: string;
         };
+        heading?: HeadingConfig;
         decodeUnicode?: boolean;
         lang?: string;
         direction?: "ltr" | "rtl";

src/constants.js

@@ -35,6 +35,63 @@ const defaultTableBorderAttributeOptions = {
   size: 1,
   stroke: 'single',
 };
+const defaultHeadingConfig = {
+  heading1: {
+    font: defaultFont,
+    fontSize: 48,
+    bold: true,
+    spacing: { before: 480, after: 0 },
+    keepLines: true,
+    keepNext: true,
+    outlineLevel: 0,
+  },
+  heading2: {
+    font: defaultFont,
+    fontSize: 36,
+    bold: true,
+    spacing: { before: 360, after: 80 },
+    keepLines: true,
+    keepNext: true,
+    outlineLevel: 1,
+  },
+  heading3: {
+    font: defaultFont,
+    fontSize: 28,
+    bold: true,
+    spacing: { before: 280, after: 80 },
+    keepLines: true,
+    keepNext: true,
+    outlineLevel: 2,
+  },
+  heading4: {
+    font: defaultFont,
+    fontSize: 24,
+    bold: true,
+    spacing: { before: 240, after: 40 },
+    keepLines: true,
+    keepNext: true,
+    outlineLevel: 3,
+  },
+  heading5: {
+    font: defaultFont,
+    fontSize: defaultFontSize,
+    bold: true,
+    spacing: { before: 220, after: 40 },
+    keepLines: true,
+    keepNext: true,
+    outlineLevel: 4,
+  },
+  heading6: {
+    font: defaultFont,
+    fontSize: 20,
+    bold: true,
+    spacing: { before: 200, after: 40 },
+    keepLines: true,
+    keepNext: true,
+    outlineLevel: 5,
+  },
+};
+
 const defaultDocumentOptions = {
   orientation: defaultOrientation,
   margins: cloneDeep(portraitMargins),
@@ -76,62 +133,7 @@ const defaultDocumentOptions = {
   numbering: {
     defaultOrderedListStyleType: 'decimal',
   },
-  heading: {
-    heading1: {
-      font: null, // use default font
-      fontSize: 48,
-      bold: true,
-      spacing: { before: 480, after: 0 },
-      keepLines: true,
-      keepNext: true,
-      outlineLevel: 0,
-    },
-    heading2: {
-      font: null, // use default font
-      fontSize: 36,
-      bold: true,
-      spacing: { before: 360, after: 80 },
-      keepLines: true,
-      keepNext: true,
-      outlineLevel: 1,
-    },
-    heading3: {
-      font: null, // use default font
-      fontSize: 28,
-      bold: true,
-      spacing: { before: 280, after: 80 },
-      keepLines: true,
-      keepNext: true,
-      outlineLevel: 2,
-    },
-    heading4: {
-      font: null, // use default font
-      fontSize: 24,
-      bold: true,
-      spacing: { before: 240, after: 40 },
-      keepLines: true,
-      keepNext: true,
-      outlineLevel: 3,
-    },
-    heading5: {
-      font: null, // use default font
-      fontSize: null, // use default font size
-      bold: true,
-      spacing: { before: 220, after: 40 },
-      keepLines: true,
-      keepNext: true,
-      outlineLevel: 4,
-    },
-    heading6: {
-      font: null, // use default font
-      fontSize: 20,
-      bold: true,
-      spacing: { before: 200, after: 40 },
-      keepLines: true,
-      keepNext: true,
-      outlineLevel: 5,
-    },
-  },
+  heading: defaultHeadingConfig,
   decodeUnicode: false,
   defaultLang,
   direction: defaultDirection,
@@ -181,6 +183,7 @@ const defaultPercentageMarginValue = 0;
 
 export {
   defaultDocumentOptions,
+  defaultHeadingConfig,
   defaultTableBorderOptions,
   defaultHTMLString,
   relsFolderName,