diffToneGen.js

let fs = require("fs");

const allPitches = JSON.parse(fs.readFileSync("./allPitches.json", "utf8"));

let produceDiffTone = {};

for (let pitchA in allPitches) {
    for (let pitchB in allPitches) {
        let diff = (Math.round(Math.abs(allPitches[pitchA] - allPitches[pitchB])*1000)/1000).toString();
        // console.log(`${pitchA} - ${pitchB} = ${diff}`);
        if (!produceDiffTone[diff]) produceDiffTone[diff] = [[pitchA, pitchB]]
        else produceDiffTone[diff].push([pitchA,pitchB])
    }
}

let allPitchesObject = [];
for (let pitch in allPitches) {
    allPitchesObject.push(parseFloat(allPitches[pitch]));
}

let allPitchNames = Object.keys(allPitches);

/*
// For each difference tone 
// Compare it to all the allPitches frequencies 
// Place it in an object under the letter name 
{
 "A4": {
    "440": "A5/A4"
 }
}
*/

let diffToneOutput = {}
    for (let pitch in allPitchNames) {
    diffToneOutput[allPitchNames[pitch]] = {};
}

for (let _diffPitch in produceDiffTone) {
    let diffPitch = parseFloat(_diffPitch);
    let closestPitch = null;
    let closestPitchErr = 9999999;
    for (let pitch in allPitches) {
        let pitchFreq = allPitches[pitch];
        let diff = Math.abs(diffPitch - pitchFreq);
        if (diff < closestPitchErr) {
            closestPitch = pitch;
            closestPitchErr = diff;
        }
    }
    diffToneOutput[closestPitch][produceDiffTone[_diffPitch][0]] = diffPitch;
}

let orderedFrequenciesRaw = Object.keys(produceDiffTone);

let txt = "";
let orderedFrequencies = [];

for (let frequency in orderedFrequenciesRaw) {
    orderedFrequencies.push(parseFloat(orderedFrequenciesRaw[frequency]));
}

orderedFrequencies.sort(function(a, b) {
  return a - b;
});

for (let frequency in orderedFrequencies) {
    txt += `${orderedFrequencies[frequency]}Hz # ${produceDiffTone[orderedFrequencies[frequency].toString()][0]}\n`
}

console.log(txt);

fs.writeFileSync("out.json",JSON.stringify(diffToneOutput))