<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Frequency Adjustment with Sine Wave</title>
</head>
<body>

<button id="startButton">Start Sound</button>

<button id="stopButton">Stop Sound</button>

<input type="range" id="frequencySlider" min="20" max="2000" value="440" step="1">
    <label for="frequencySlider">Frequency (Hz): <span id="frequencyValue">440</span></label>

// Variable to hold the oscillator node
        let oscillator;

// Create a gain node to control the volume of the sound
        const gainNode = audioContext.createGain();

// Connect the gain node to the audio context's destination (the speakers)
        gainNode.connect(audioContext.destination);

// Function to create a new oscillator
        function createOscillator() {
            // Create a new oscillator node
            oscillator = audioContext.createOscillator();

// Get the current value of the frequency slider
            const frequency = document.getElementById('frequencySlider').value;

// Set the oscillator type to 'sine' for a basic sine wave
            oscillator.type = 'sine';

// Set the frequency of the oscillator to the current value of the slider
            oscillator.frequency.setValueAtTime(frequency, audioContext.currentTime);

// Set the gain to 0.5 (half the maximum volume)
            gainNode.gain.setValueAtTime(0.5, audioContext.currentTime);

// Connect the oscillator to the gain node
            oscillator.connect(gainNode);
        }

// Add an event listener for the start button to begin playing the sound
        document.getElementById('startButton').addEventListener('click', function() {
            // Create and start a new oscillator when the button is clicked (if not already playing)
            if (!oscillator || oscillator.context.state === 'closed') {
                createOscillator();
                oscillator.start();
            }
        });

// Add an event listener for the stop button to stop the sound
        document.getElementById('stopButton').addEventListener('click', function() {
            if (oscillator) {
                // Stop the oscillator when the stop button is clicked
                oscillator.stop();
                oscillator = null; // Reset oscillator after stopping
            }
        });

// Add an event listener for the frequency slider to adjust the frequency
        document.getElementById('frequencySlider').addEventListener('input', function(event) {
            // Get the current value from the slider and update the frequency
            const newFrequency = event.target.value;
            if (oscillator) {
                oscillator.frequency.setValueAtTime(newFrequency, audioContext.currentTime);
            }
            // Update the frequency display
            document.getElementById('frequencyValue').textContent = newFrequency;
        });
    </script>

</body>
</html>

About THIS CODE (CANVASOR.NET):