Added new row for ETA time and fixed a stupid date manipulation bug.

www/index.html

@@ -18,6 +18,7 @@
         <h1>Bitcoin Block Halving Countdown!</h1>
         <h3><span id="blocksleft">...</span> blocks left</h3>
         <h3><span id="timeleft">... remaining</span></h3>
+        <h3 id="halftimectr"><span id="halftime">ETA ...</span></h3>
         <p>
           Click/tap on the rows for more statistics - <a href="#faq">FAQ</a>
         </p>

www/main.js

@@ -90,7 +90,7 @@ function toggleElemSelected(elem) {
 function formatDate(date) {
     let year = date.getUTCFullYear();
     let month = "0" + (1 + date.getUTCMonth());
-    let day = "0" + (1 + date.getUTCDate());
+    let day = "0" + date.getUTCDate();
     let hours = "0" + date.getUTCHours();
     let minutes = "0" + date.getUTCMinutes();
     let seconds = "0" + date.getUTCSeconds();
@@ -150,7 +150,7 @@ function makeBlockElem(block, prevBlock) {
     // Make the timestamp element.
     let timestampElem = document.createElement("span");
     let timestampDate = new Date(block.timestamp * 1000);
-    timestampElem.innerHTML = formatDate(timestampDate);
+    timestampElem.innerHTML = formatDate(timestampDate) + " UTC";
     dataElem.appendChild(timestampElem);
 
     // this makes it look a lot nicer
@@ -251,6 +251,7 @@ function makeBlockElem(block, prevBlock) {
 
 var blocksLeftElem = null;
 var timeLeftElem = null;
+var halfTimeElem = null;
 
 function updateRemainingCount(block) {
     if (blocksLeftElem == null) {
@@ -261,11 +262,20 @@ function updateRemainingCount(block) {
         timeLeftElem = document.getElementById("timeleft");
     }
 
+    if (halfTimeElem == null) {
+        halfTimeElem = document.getElementById("halftime");
+    }
+
     let blocksLeft = nextHalvingHeight - curTipBlock.height;
     blocksLeftElem.innerHTML = blocksLeft.toString()
 
     if (blocksLeft < 1) {
         timeLeftElem.innerHTML = "Halving imminent!";
+
+        // Hide the expected time.
+        let timectr = document.getElementById("halftimectr");
+        timectr.style.display = "none";
+
     } else {
         let nowUnix = Date.now() / 1000; // wtf???
 
@@ -286,6 +296,14 @@ function updateRemainingCount(block) {
         }
 
         timeLeftElem.innerHTML = "roughly " + acc + " remaining";
+
+        // Reward halving date.
+        let localNow = new Date();
+        let tzOff = (new Date()).getTimezoneOffset() * 60 * 1000;
+        let etaDate = new Date(localNow.getTime() + (secsLeft * 1000) - tzOff);
+        let formattedEtaDate = formatDate(etaDate);
+        halfTimeElem.innerHTML = "around " + formattedEtaDate + " local time";
+
     }
 }