JSFiddle - React, Tailwind, and code Playground

Babel + JSX

let audioCtx = new AudioContext();

// Create nodes
let osc = audioCtx.createOscillator();
let gain = audioCtx.createGain();

// Set parameters
osc.frequency.value = 440;
gain.gain.value = 0;

// Schedule parameter changes
// Start ramping up to 1 right away, with a suitable time
// constant.
gain.gain.setValueAtTime(0, 0);
gain.gain.setTargetAtTime(1, 0, 5);

// Connect graph
osc.connect(gain);
gain.connect(audioCtx.destination);

// Schedule start and stop
osc.start();
osc.stop(audioCtx.currentTime + 3);