const fetch = (url) => new Promise((resolve, reject) => {
    const listener = ({ srcElement: req }) => {
        req.status === 200 ? resolve(req.responseText) : reject("busted");
    };

    const req = new XMLHttpRequest();
    req.addEventListener('load', listener);
    req.open('GET', url);
    req.send();
});

const main = function(strData) {
    const json = JSON.parse(strData);
    const metaMatrix = Matrices.buildMetaMatrix(json, "1930");
    const chordMatrix = Matrices.buildChordMatrix(json, "1930");
    Diagram.build("1930", json, metaMatrix, chordMatrix);
}

fetch('worldcup.json').then(main);