caching link content for link preview

_includes/link-previews.html

@@ -50,6 +50,8 @@
   var tooltipWrapper = document.getElementById('tooltip-wrapper')
   var tooltipContent = document.getElementById('tooltip-content')
 
+  var linkHistories = {};
+
   function hideTooltip() {
     opacityTimeout = setTimeout(function() {
       tooltipWrapper.style.opacity = 0;
@@ -66,6 +68,7 @@
     var top = window.pageYOffset || document.documentElement.scrollTop
 
     if (event.target.host === window.location.host) {
+      if (!linkHistories[event.target.href]) {
         iframe.src = event.target.href
         iframe.onload = function() {
           tooltipContentHtml = ''
@@ -73,12 +76,21 @@
           tooltipContentHtml += iframe.contentWindow.document.querySelector('content').innerHTML
 
           tooltipContent.innerHTML = tooltipContentHtml
+          linkHistories[event.target.href] = tooltipContentHtml
 
           tooltipWrapper.style.display = 'block';
           setTimeout(function() {
             tooltipWrapper.style.opacity = 1;
           }, 1)
         } 
+      } else {
+        tooltipContent.innerHTML = linkHistories[event.target.href]
+        tooltipWrapper.style.display = 'block';
+        setTimeout(function() {
+          tooltipWrapper.style.opacity = 1;
+        }, 1)
+      }
+
 
       tooltipWrapper.style.left = elem_props.left - (tooltipWrapper.offsetWidth / 2) + (elem_props.width / 2) + "px";
       if ((window.innerHeight - elem_props.top) < (tooltipWrapper.offsetHeight)) {

_notes/your-first-note.md

@@ -58,6 +58,8 @@ Notice in the "Notes mentioning this note" section that there is another note li
 
 If you're on a device with mouse support, try hovering your mouse on internal links to preview the notes: [[a note about cats]].
 
+Links that have been previewed will be cached to avoid redundant requests.
+
 ### Images and other Markdown goodies
 
 Finally, because you have the full power of Markdown in this template, you can use regular Markdown syntax for various formatting options.