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) {
    function stringify(val) {
        switch(val.t){
    		case 'n': return val.v;
    		case 's': case 'str': return JSON.stringify(val.v);
    		default: throw 'unrecognized type ' + val.t;
    	}
    }
	if(sheet["!ref"]) {
		var r = XLSX.utils.decode_range(sheet["!ref"]);
		for(var R = r.s.r; R <= r.e.r; ++R) {
			var row = [];
			for(var C = r.s.c; C <= r.e.c; ++C) {
				var val = sheet[XLSX.utils.encode_cell({c:C,r:R})];
				row.push(val ? stringify(val) : "");
			}
			out.innerText += (row.join(",") + "\n");
		}
	}
}

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'});
            if(get_radio_value("format") === "json"){
                out.innerText = JSON.stringify(to_json(xlsx), 2, 2);
            } else {
                to_csv(xlsx.Sheets[xlsx.SheetNames[0]]);
            }
		};
		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>