Save data as file via JavaScript

function saveFile(name, blob) {
    var w = window;
    var d = w.document;
    var link = d.createElement('a');
    link.setAttribute('download', name);
    link.href = w.URL.createObjectURL(blob);
    link.onclick = function () {
        d.body.removeChild(this);
    };
    link.style.display = 'none';
    d.body.appendChild(link);
    link.click();
}

saveFile('hello.txt', new Blob(['Hello, world!']));