Introduce some functional programming techniques

src/file/paragraph/links/bookmark-attributes.ts

@@ -1,23 +1,23 @@
 import { XmlAttributeComponent } from "file/xml-components";
 
 export interface IBookmarkStartAttributesProperties {
-    id: string;
-    name: string;
+    readonly id: string;
+    readonly name: string;
 }
 
 export class BookmarkStartAttributes extends XmlAttributeComponent<IBookmarkStartAttributesProperties> {
-    protected xmlKeys = {
+    protected readonly xmlKeys = {
         id: "w:id",
         name: "w:name",
     };
 }
 
 export interface IBookmarkEndAttributesProperties {
-    id: string;
+    readonly id: string;
 }
 
 export class BookmarkEndAttributes extends XmlAttributeComponent<IBookmarkEndAttributesProperties> {
-    protected xmlKeys = {
+    protected readonly xmlKeys = {
         id: "w:id",
     };
 }

src/file/paragraph/links/bookmark.ts

@@ -1,16 +1,12 @@
 // http://officeopenxml.com/WPbookmark.php
-
 import { XmlComponent } from "file/xml-components";
 import { TextRun } from "../run";
 import { BookmarkEndAttributes, BookmarkStartAttributes } from "./bookmark-attributes";
 
 export class Bookmark {
-    public linkId: number;
-
+    public readonly linkId: number;
     public readonly start: BookmarkStart;
-
     public readonly text: TextRun;
-
     public readonly end: BookmarkEnd;
 
     constructor(name: string, text: string, relationshipsCount: number) {
@@ -23,7 +19,7 @@ export class Bookmark {
 }
 
 export class BookmarkStart extends XmlComponent {
-    public linkId: number;
+    public readonly linkId: number;
 
     constructor(name: string, relationshipsCount: number) {
         super("w:bookmarkStart");
@@ -39,7 +35,7 @@ export class BookmarkStart extends XmlComponent {
 }
 
 export class BookmarkEnd extends XmlComponent {
-    public linkId: number;
+    public readonly linkId: number;
 
     constructor(relationshipsCount: number) {
         super("w:bookmarkEnd");

src/file/paragraph/links/hyperlink-attributes.ts

@@ -1,13 +1,13 @@
 import { XmlAttributeComponent } from "file/xml-components";
 
 export interface IHyperlinkAttributesProperties {
-    id?: string;
-    anchor?: string;
-    history: number;
+    readonly id?: string;
+    readonly anchor?: string;
+    readonly history: number;
 }
 
 export class HyperlinkAttributes extends XmlAttributeComponent<IHyperlinkAttributesProperties> {
-    protected xmlKeys = {
+    protected readonly xmlKeys = {
         id: "r:id",
         history: "w:history",
         anchor: "w:anchor",

src/file/paragraph/links/hyperlink.ts

@@ -1,11 +1,10 @@
 // http://officeopenxml.com/WPhyperlink.php
-
 import { XmlComponent } from "file/xml-components";
 import { TextRun } from "../run";
 import { HyperlinkAttributes, IHyperlinkAttributesProperties } from "./hyperlink-attributes";
 
 export class Hyperlink extends XmlComponent {
-    public linkId: number;
+    public readonly linkId: number;
 
     constructor(text: string, relationshipsCount: number, anchor?: string) {
         super("w:hyperlink");
@@ -14,14 +13,10 @@ export class Hyperlink extends XmlComponent {
 
         const props: IHyperlinkAttributesProperties = {
             history: 1,
+            anchor: anchor ? anchor : undefined,
+            id: !anchor ? `rId${this.linkId}` : undefined,
         };
 
-        if (anchor) {
-            props.anchor = anchor;
-        } else {
-            props.id = `rId${this.linkId}`;
-        }
-
         const attributes = new HyperlinkAttributes(props);
         this.root.push(attributes);
         this.root.push(new TextRun(text).style("Hyperlink"));