sheetjs/index.html

<style>
#drop{
	border:2px dashed #bbb;
	-moz-border-radius:5px;
	-webkit-border-radius:5px;
	border-radius:5px;
	padding:25px;
	text-align:center;
	font:20pt bold,"Vollkorn";color:#bbb
}
</style>
<b>JS-XLSX</b><br />
<input type="radio" name="format" value="csv" checked> CSV<br>
<input type="radio" name="format" value="json"> JSON<br>

<div id="drop">Drop an XLSX file here to see the output in CSV.</div>
<pre id="out"></pre>
<br />
<script src="jszip.js"></script>
<script src="xlsx.js"></script>
<script>
function get_radio_value( radioName ) {
	var radios = document.getElementsByName( radioName );
	for( var i = 0; i < radios.length; i++ ) {
		if( radios[i].checked ) {
			return radios[i].value;
		}
	}
}

//Row object array form:
//Each row is an object with column headers as keys
function to_json(workbook) {
	var result = {};
	workbook.SheetNames.forEach(function(sheetName) {
		var rObjArr = XLSX.utils.sheet_to_row_object_array(workbook.Sheets[sheetName]);
		if(rObjArr.length > 0){
			result[sheetName] = rObjArr;
		}
	});
	return result;
}


function to_csv(sheet) {
	return XLSX.utils.sheet_to_csv(sheet);
}

var drop = document.getElementById('drop');
function handleDrop(e) {
	e.stopPropagation();
	e.preventDefault();
	var files = e.dataTransfer.files;
	var i,f;
	for (i = 0, f = files[i]; i != files.length; ++i) {
		var reader = new FileReader();
		var name = f.name;
		reader.onload = function(e) {
			var data = e.target.result;
			var xlsx = XLSX.read(data, {type: 'binary'});
			var output = "";
			if(get_radio_value("format") === "json"){
				output = JSON.stringify(to_json(xlsx), 2, 2);
			} else {
				output = to_csv(xlsx.Sheets[xlsx.SheetNames[0]]);
			}
			out.innerText = output;
		};
		reader.readAsBinaryString(f);
	}
}

function handleDragover(e) {
	e.stopPropagation();
	e.preventDefault();
	e.dataTransfer.dropEffect = 'copy';
}
drop.addEventListener('dragover', handleDragover, false);
drop.addEventListener('drop', handleDrop, false);
</script>