Initiates a file download from javascript. No longer works from within sandboxed iframes.

downloadString.js

function downloadString(data, fileName = 'download.txt', fileType = 'text/plain') {
    var blob = new Blob([data], {type: fileType});
    if (window.navigator && window.navigator.msSaveOrOpenBlob) {
        window.navigator.msSaveOrOpenBlob(blob, fileName);
    } else{
        var e = document.createEvent('MouseEvents'),
        a = document.createElement('a');
        a.download = fileName;
        a.href = window.URL.createObjectURL(blob);
        a.dataset.downloadurl = [fileType, a.download, a.href].join(':');
        e.initEvent('click', !0, !1, window, 0, 0, 0, 0, 0, !1, !1, !1, !1, 0, null);
        a.dispatchEvent(e);
    }
}

// Usage example
// let content = 'a, b, c\n1, 2, 3';
// downLoadString(content, 'content.csv', 'text/csv');