[WIP] Add ability to play sound

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

content/blog/music_theory/playsound.js

@@ -0,0 +1,15 @@
+window.addEventListener("load", (event) => {
+    for (const elt of document.getElementsByClassName("mt-sound-play-button")) {
+        elt.addEventListener("click", (event) => {
+            const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
+            for (const freq of event.target.getAttribute("data-sound-info").split(",")) {
+                const oscillator = audioCtx.createOscillator();
+                oscillator.type = "sine";      // waveform: sine, square, sawtooth, triangle
+                oscillator.frequency.value = parseInt(freq); // Hz
+                oscillator.connect(audioCtx.destination);
+                oscillator.start();
+                oscillator.stop(audioCtx.currentTime + 2); // stop after 1 second
+            }
+        });
+    }
+});