saveExcel function

saveExcel.js

function saveExcel(data, filename){
    
	var datenum = function (v, date1904) {
        if(date1904) v+=1462;
        var epoch = Date.parse(v);
        return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
    },
    sheet_from_array_of_arrays = function (data, opts) {
        var ws = {};
        var range = {s: {c:10000000, r:10000000}, e: {c:0, r:0 }};
        for(var R = 0; R != data.length; ++R) {
            for(var C = 0; C != data[R].length; ++C) {
                if(range.s.r > R) range.s.r = R;
                if(range.s.c > C) range.s.c = C;
                if(range.e.r < R) range.e.r = R;
                if(range.e.c < C) range.e.c = C;
                var cell = {v: data[R][C] };
                if(cell.v == null) continue;
                var cell_ref = XLSX.utils.encode_cell({c:C,r:R});

                if(typeof cell.v === 'number') cell.t = 'n';
                else if(typeof cell.v === 'boolean') cell.t = 'b';
                else if(cell.v instanceof Date) {
                    cell.t = 'n'; 
                    cell.z = XLSX.SSF._table[14];
                    cell.v = datenum(cell.v);
                }
                else cell.t = 's';

                ws[cell_ref] = cell;
            }
        }
        if(range.s.c < 10000000) ws['!ref'] = XLSX.utils.encode_range(range);
        return ws;
    },
	Workbook = function () {
        if(!(this instanceof Workbook)) return new Workbook();
        this.SheetNames = [];
        this.Sheets = {};
    },
	s2ab = function (s) {
        var buf = new ArrayBuffer(s.length);
        var view = new Uint8Array(buf);
        for (var i=0; i!=s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
        return buf;
    },
    obj2array = function(data){
        if(!(data[0] instanceof Array)){
            
            var keys = Object.keys(data[0]),
                arrdata = [];
            data.forEach(function(obj){
                if(Object.keys(obj).length > keys.length){
                    keys = Object.keys(obj);
                }
            });
            data.forEach(function(obj){
                var arr = [];
                
                keys.forEach(function(key){
                    arr.push(obj[key]);
                })
                //console.log(arr)
                arrdata.push(arr);
            })
            //console.log(keys, data);
            data = [keys].concat(arrdata);
        }
        //console.log(data);
        return data;
    },
    wb = new Workbook(),
    array_buffer,
	file;

    if(typeof data === 'string' && ~data.indexOf('<table')){

        node = document.createElement('div');
        node.innerHTML = data;
        wb.SheetNames.push('Sheet1');
        wb.Sheets['Sheet1'] = XLSX.utils.table_to_book(node.getElementsByTagName('table')[0]).Sheets['Sheet1'];

    } else if(data instanceof Array){

        wb.SheetNames.push('Sheet1');
        wb.Sheets['Sheet1'] = sheet_from_array_of_arrays(obj2array(data));
        
	}else{
        
		Object.keys(data).forEach(function(sheet_name){
            var sheet_data = data[sheet_name];
            if(typeof sheet_data === 'string' && ~sheet_data.indexOf('<table')){

                node = document.createElement('div');
                node.innerHTML = sheet_data;
                wb.SheetNames.push(sheet_name);
                wb.Sheets[sheet_name] = XLSX.utils.table_to_book(node.getElementsByTagName('table')[0]).Sheets['Sheet1'];

            }else{
                wb.SheetNames.push(sheet_name);
                wb.Sheets[sheet_name] = sheet_from_array_of_arrays(obj2array(sheet_data));
            }
        });
        
	}
	array_buffer = s2ab(XLSX.write(wb, {bookType:'xlsx', bookSST:true, type: 'binary'}));
    file = new Blob([array_buffer],{type:'application/octet-stream'});
    saveAs(file, (filename||'data')+'.xlsx')
}

Usage

html

<script src="https://fastcdn.org/FileSaver.js/1.1.20151003/FileSaver.min.js"></script>
<script type="text/javascript" src="//unpkg.com/xlsx/dist/xlsx.full.min.js"></script>

javascript

var data_table = [
    [1,2,3],
    [4,5,6]
];
saveExcel(data_table);

// multiple sheets
saveExcel({
   "Sheet1_name": data_table1,
   "Sheet2_name": data_table2,
});

// or from html table
saveExcel('\
<table>\
    <tr>\
         <td colspan=2>Data</td>\
    </tr>\
    <tr>\
         <td>Data1</td>\
         <td>Data2</td>\
    </tr>\
</table>\
')