convert currency into another via USD currency

convert-via-usd.js

convert_currency = (rates, from, to) => {
    const conversions = {};
    // 1.45 / (0.0070 * 110)

    
    for(let i=0; i<rates.length; i++) {
        if (!conversions[rates[i][0]]) {
            conversions[rates[i][0]] = {};
        }
        conversions[rates[i][0]][rates[i][1]] = rates[i][2];
    }

    for(let i=0; i<rates.length; i++) {
        if (!conversions.usd[rates[i][1]]) {
            conversions.usd[ rates[i][1] ] = (rates[i][2] * conversions.usd[ rates[i][0] ])
        }
    }
        console.log(conversions);

    if (conversions[from]?.[to]) return conversions[from][to];
    if (to === 'usd') return 1 / conversions.usd[from];



    return conversions.usd[to] / conversions.usd[from];

};

convert_currency([
    ['usd', 'jpy', 110],
    ['usd', 'aud', 1.45],
    ['jpy', 'gbp', 0.0070]],
    'gbp',
    'usd'
);