JSFiddle - React, Tailwind, and code Playground

by RDIFB0

JavaScript

var maxValue = function(data) {
	var max = 0;
	var maxIndex = 0;
	for(var i=0; i < data.length; i++) {
		if(data[i] > max) {
			max = data[i];
			maxIndex = i;
		}
	}
	return maxIndex;
}

var data = [235, 255, 255, 255, 255, 191, 167, 197, 211, 208, 202, 188, 172, 189, 196, 190, 178, 147, 141, 149, 151, 145, 137, 112, 134, 145, 144, 129, 110, 133, 142, 142, 136, 129, 109, 123, 116, 108, 103, 107, 105, 115, 121, 121, 106, 114, 120, 113, 111, 107, 97, 97, 111, 115, 111, 94, 95, 107, 115, 117, 108, 82, 76, 102];
var index = maxValue(data);

var sampleRate = 44100 // context.sampleRate;
var fftSize = 128 // analyser.fftSize;
var freq = index * (sampleRate / fftSize / 2.0);

alert('Max peak frequency = X Hz'.replace('X', freq.toFixed(2)));