Download the contents of a HTML element

download.js

var downloadButton = document.getElementById('downloadButton');
downloadButton.addEventListener('click', function () {
    var contents = document.getElementById('someDiv').innerHTML;

    if (contents.length = 0) {
        return;
    }

    var filename = 'some-filename.txt';

    if (navigator.msSaveBlob) { // IE
        navigator.msSaveBlob(new Blob([contents], { type: 'text/plain;charset=utf-8;' }), filename);
    } else {
        var link = document.createElement('a');
        link.setAttribute('download', filename);
        link.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(contents));
        document.body.append(link);
        link.click();
        document.body.removeChild(link);
    }
});