Fix for bug futurepress#1367

src/book.js

@@ -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 +15,9 @@ class Navigation {
 		this.landmarksByType = {};
 
 		this.length = 0;
+		if (navPath) {
+			this.tocPath = new Path(navPath)
+		}
 		if (xml) {
 			this.parse(xml);
 		}
@@ -198,7 +202,8 @@ class Navigation {
 			return;
 		}
 
-		let src = content.getAttribute("href") || "";
+		const href = content.getAttribute("href") || "";
+		let src = this.tocPath.join(href)
 
 		if (!id) {
 			id = src;

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
 	 *