client demo

+let rec = null;
+let audioStream = null;
+const recordButton = document.getElementById("recordButton");
+const transcribeButton = document.getElementById("transcribeButton");
+recordButton.addEventListener("click", startRecording);
+transcribeButton.addEventListener("click", transcribeText);
+function startRecording() {
+    let constraints = { audio: true, video:false }
+    recordButton.disabled = true;
+    transcribeButton.disabled = false;
+    navigator.mediaDevices.getUserMedia(constraints).then(function(stream) {
+        const audioContext = new window.AudioContext();
+        audioStream = stream;
+        const input = audioContext.createMediaStreamSource(stream);
+        rec = new Recorder(input, { numChannels:1 })
+        rec.record()
+    }).catch(function(err) {
+        recordButton.disabled = false;
+        transcribeButton.disabled = true;
+    });
+}
+function transcribeText() {
+    transcribeButton.disabled = true;
+    recordButton.disabled = false;
+    rec.stop();
+    audioStream.getAudioTracks()[0].stop();
+    rec.exportWAV(uploadSoundData);
+}
+function uploadSoundData(blob) {
+    let filename = new Date().toISOString();
+    let xhr = new XMLHttpRequest();
+    let formData = new FormData();
+    xhr.onload = function(e) {
+        if(this.readyState === 4) {
+            document.getElementById("output").innerHTML += `<br><br><strong>Result: </strong>${e.target.responseText}`
+        }
+    };
+    formData.append("audio_data", blob, filename);
+    xhr.open("POST", "/upload_sound", true);
+    xhr.send(formData);
+}
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