add random chance of playing

index.html

@@ -15,6 +15,13 @@
 		<img class="pipe" src="/pipe.jpg" alt="metal pipe from metal pipe fallout sound effect videos">
 	</p>
 	<p><button id="play-now">play now</button></p>
+	<p>
+		<input type="checkbox" id="play-at-random">
+		<label for="play-at-random">play at random</label>
+	</p>
+	<p>
+		<label>one in <input type="number" min="0" value="100" id="random-chance"> chance of playing every minute</label>
+	</p>
 </body>
 
 </html>

index.js

@@ -3,6 +3,10 @@
 
   const pipefall = document.getElementById("pipefall");
   const now = document.getElementById("play-now");
+  const playAtRandom = document.getElementById("play-at-random");
+  const randomChance = document.getElementById("random-chance");
+
+  playAtRandom.checked = false;
 
   const play = () => {
     console.log("pipefall!");
@@ -14,4 +18,24 @@
   for (let pipe of document.querySelectorAll(".pipe")) {
     pipe.addEventListener("click", play);
   }
+
+  function random(max) {
+    return Math.floor(Math.random() * max);
+  }
+
+  let timeSincePlay = 0;
+  setInterval(() => {
+    if (playAtRandom.checked) {
+      timeSincePlay += 1;
+      if (timeSincePlay >= 60) {
+        const v = random(randomChance.value);
+        if (v === 0) {
+          play();
+          timeSincePlay = 0;
+        }
+      }
+    } else {
+      timeSincePlay = 0;
+    }
+  }, 1000);
 })();