docs: "API Reference" support added

docs/api.md

@@ -0,0 +1,74 @@
+---
+hide:
+  - navigation
+  - toc
+---
+
+<script src="../javascripts/jquery.min.js"></script>
+<script src="../javascripts/iframeResizer.min.js"></script>
+
+<iframe id="apiIframe" style="width: 100%; border: none;"></iframe>
+
+<script>
+// injects scripts to the iframe source code
+$('#apiIframe').on('load', function() {
+  body = $(this).contents().find('body');
+  body.append('<scr' + 'ipt src="../../javascripts/iframeResizer.contentWindow.min.js"></scr' + 'ipt>');
+  body.append('<scr' + 'ipt>' +
+    'var links = document.querySelectorAll("a");' +
+    'for (var i = 0; i < links.length; i++) {' +
+    '  links[i].addEventListener("click", whichLinkWasClicked);' +
+    '}' +
+    '' +
+    'function whichLinkWasClicked(evt) {' +
+    '  window.parentIFrame.sendMessage(evt.target.href);' +
+    '  evt.preventDefault();' +
+    '}' +
+  '</scr' + 'ipt>');
+});
+
+// reloads the window with the content when a user navigates over the browser's history
+function locationHashChanged() {  
+  window.location.reload();
+}
+window.onhashchange = locationHashChanged;
+
+apiIframe = document.getElementById('apiIframe');
+hash = window.location.hash;
+if (hash.length == 0) {
+  // sets default hash for the API Reference
+  hash = "#full";
+  history.pushState(null, "", hash);
+}
+
+// set the iframe source based on the hash in the URL
+if (hash.startsWith("#wg21.link/")) {
+  apiIframe.src = "https://" +  hash.slice(1);
+  apiIframe.height = 900;
+}
+else
+  apiIframe.src = "gen/" +  hash.slice(1) + ".html";
+
+// receives content height from the subpage displayed in the iframe
+// works only for the pages in the same domain as the main docs
+iFrameResize({
+  scrolling: "yes",
+
+  // obtains the link URL clicked in the subpage
+  onMessage: function(messageData) {
+    url = messageData.message;
+    if (url.startsWith("https://wg21.link/")) {
+      hash = '#' + messageData.message.replace("https://", "");
+    }
+    else {
+      pos = messageData.message.indexOf('#');
+      if(pos == -1) {
+        pos = messageData.message.lastIndexOf('/');
+      }
+      hash = '#' + messageData.message.slice(pos + 1);
+    }
+    history.pushState(null, "", hash);
+    window.location.reload();
+  }
+},'#apiIframe')
+</script>