The channelCount property of the AudioNode interface represents an integer used to determine how many channels are used when up-mixing and down-mixing connections to any inputs to the node.
channelCount's usage and precise definition depend on the value of AudioNode.channelCountMode:
channelCountMode value is max.channelCountMode value is clamped-max.channelCountMode value is explicit.An integer.
const audioCtx = new AudioContext();
const oscillator = audioCtx.createOscillator();
const gainNode = audioCtx.createGain();
oscillator.connect(gainNode);
gainNode.connect(audioCtx.destination);
oscillator.channelCount;