fix: navigation does not work in diff folders

src/book.js

@@ -502,9 +502,9 @@ class Book {
 					this.opening.resolve(this);
 				});
 			})
-			.catch((err) => {
-				console.error(err);
-			});
+				.catch((err) => {
+					console.error(err);
+				});
 		} else {
 			// Resolve book opened promise
 			this.loaded.displayOptions.then(() => {
@@ -547,7 +547,7 @@ class Book {
 
 		return this.load(navPath, "xml")
 			.then((xml) => {
-				this.navigation = new Navigation(xml);
+				this.navigation = new Navigation(xml, navPath);
 				this.pageList = new PageList(xml);
 				return this.navigation;
 			});

src/navigation.js

@@ -1,11 +1,12 @@
 import {qs, qsa, querySelectorByType, filterChildren, getParentByTagName} from "./utils/core";
+import Path from "./utils/path";
 
 /**
  * Navigation Parser
  * @param {document} xml navigation html / xhtml / ncx
  */
 class Navigation {
-	constructor(xml) {
+	constructor(xml, navPath = "") {
 		this.toc = [];
 		this.tocByHref = {};
 		this.tocById = {};
@@ -14,6 +15,11 @@ class Navigation {
 		this.landmarksByType = {};
 
 		this.length = 0;
+
+		if (navPath) {
+			this.tocPath = new Path(navPath);
+		}
+		
 		if (xml) {
 			this.parse(xml);
 		}
@@ -198,7 +204,8 @@ class Navigation {
 			return;
 		}
 
-		let src = content.getAttribute("href") || "";
+		const href = content.getAttribute("href") || "";
+		let src = this.tocPath.join(href);
 		
 		if (!id) {
 			id = src;
@@ -317,7 +324,7 @@ class Navigation {
 				parentNode = item.parentNode,
 				parent;
 
-		if(parentNode && (parentNode.nodeName === "navPoint" || parentNode.nodeName.split(':').slice(-1)[0] === "navPoint")) {
+		if(parentNode && (parentNode.nodeName === "navPoint" || parentNode.nodeName.split(":").slice(-1)[0] === "navPoint")) {
 			parent = parentNode.getAttribute("id");
 		}
 

src/utils/path.js

@@ -58,6 +58,17 @@ class Path {
 		return (what.charAt(what.length-1) === "/");
 	}
 
+	/**
+	 * Join a paths
+	 *
+	 * https://nodejs.org/api/path.html#pathjoinpaths
+	 * @param	{string} what
+	 * @returns {string} joined path
+	 */
+	join (what) {
+		return path.join(this.directory, what);
+	}
+
 	/**
 	 * Resolve a path against the directory of the Path
 	 *