file.js

//code for importing and exporting the data
theData = null;
function loadData(file)
{
	var r = new FileReader();
	r.onload = (function(f) {
		return function(e) {
			parseFile(e.target.result);
		}
	})(file[0]);
	r.readAsText(file[0]);//asynchron reading
}

function saveData()
{
	if(theData == null)
	{
		alert("No Data loaded");
		return;
	}
	var d = new Date();
	var filename = "noten_" + d.toISOString() + ".myjson";
	var data = JSON.stringify(theData, undefined, 2);
	var s = d3.select("body").append("a").html("download").attr("href", 'data:application/octet-stream;charset=utf-8,' + encodeURIComponent(data)).attr("download", filename).attr("id", "downloadlink");
	s[0][0].click();
	s.remove();
}

function parseFile(s)
{
	theData = JSON.parse(s);
	drawMainMenu();
}
function newJson()
{
	theData = {};
	drawMainMenu();
}