add support for caching nomadnet pages in memory

public/index.html

@@ -638,6 +638,7 @@
                 nodePageContent: null,
                 nodePageProgress: 0,
                 nodePagePathHistory: [],
+                nodePageCache: {},
 
                 isDownloadingNodeFile: false,
                 nodeFilePath: null,
@@ -1162,7 +1163,7 @@
                     // do nothing if failed to load messages
                 }
             },
-            async loadNodePage(destinationHash, pagePath, addToHistory = true) {
+            async loadNodePage(destinationHash, pagePath, addToHistory = true, loadFromCache = true) {
 
                 // get new sequence for this page load
                 const seq = ++this.nodePageRequestSequence;
@@ -1181,6 +1182,22 @@
                     this.nodePagePathHistory.push(previousNodePagePath);
                 }
 
+                // check if we can load this page from the cache
+                if(loadFromCache){
+
+                    // load from cache
+                    const nodePagePathCacheKey = `${destinationHash}:${pagePath}`;
+                    const cachedNodePageContent = this.nodePageCache[nodePagePathCacheKey];
+
+                    // if page is cache, we can just return it now
+                    if(cachedNodePageContent != null){
+                        this.nodePageContent = cachedNodePageContent;
+                        this.isLoadingNodePage = false;
+                        return;
+                    }
+
+                }
+
                 this.downloadNomadNetPage(destinationHash, pagePath, (pageContent) => {
 
                     // do nothing if callback is for a previous request
@@ -1197,6 +1214,10 @@
                         this.nodePageContent = pageContent;
                     }
 
+                    // update cache
+                    const nodePagePathCacheKey = `${destinationHash}:${pagePath}`;
+                    this.nodePageCache[nodePagePathCacheKey] = this.nodePageContent;
+
                     // update page content
                     this.isLoadingNodePage = false;
 
@@ -1227,8 +1248,8 @@
             },
             async reloadNodePage() {
 
-                // reload current node page without adding to history
-                this.onNodePageUrlClick(this.nodePagePath, false);
+                // reload current node page without adding to history and without using cache
+                this.onNodePageUrlClick(this.nodePagePath, false, false);
 
             },
             async loadPreviousNodePage() {
@@ -1281,7 +1302,7 @@
                 return null;
 
             },
-            onNodePageUrlClick: function(url, addToHistory = true) {
+            onNodePageUrlClick: function(url, addToHistory = true, useCache = true) {
 
                 // open http urls in new tab
                 if(url.startsWith("http://") || url.startsWith("https://")){
@@ -1342,7 +1363,7 @@
                     };
 
                     // navigate to node page
-                    this.loadNodePage(destinationHash, parsedUrl.path, addToHistory);
+                    this.loadNodePage(destinationHash, parsedUrl.path, addToHistory, useCache);
                     return;
 
                 }