Convert an HTML table element to an Excel spreadsheet

tableToExcel.js

function createExcelDownloadLink(xml, filename){
	var a = document.createElement('a');
	a.href = 'data:application/vnd.ms-excel, '+encodeURIComponent(xml);
	a.download = filename;
	return a;
}

//note: this doesn't work with complicated tables (e.g., merged cells)
function tableToExcel(tableElem, title, sheetname){
	
	var xml,
		elem, e,
		row, r,
		headerRows = 0, headerComplete,
		rowCount = 0, columnCount = 0;
	
	function addRow(row, styleID){
		
		var cell, c, data, dataType;
		
		xml += '<Row>',
		cell = row.children;
		for(c=0; c<cell.length; c++){
			data = cell[c].textContent;
			dataType = /^-?\d+(\.\d+)?$/.test(data) ? 'Number' : 'String';
			xml += '<Cell'+(styleID ? ' ss:StyleID="'+styleID+'"' : '')+'><Data ss:Type="'+dataType+'">'+data+'</Data></Cell>';
		}
		xml += '</Row>';
		
		rowCount++;
		if(!columnCount) columnCount = cell.length;
		
	}
	
	xml = '<?xml version="1.0" encoding="UTF-8"?><?mso-application progid="Excel.Sheet"?>'+
		'<Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"'+
				' xmlns:o="urn:schemas-microsoft-com:office:office"'+
				' xmlns:x="urn:schemas-microsoft-com:office:excel"'+
				' xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"'+
				' xmlns:html="http://www.w3.org/TR/REC-html40">';
	if(title){ xml +=
			'<DocumentProperties xmlns="urn:schemas-microsoft-com:office:office">'+
				'<Title>'+title+'</Title>'+
			'</DocumentProperties>';
	}
	xml +=	'<ExcelWorkbook xmlns="urn:schemas-microsoft-com:office:excel">'+
				'<ProtectStructure>False</ProtectStructure>'+
				'<ProtectWindows>False</ProtectWindows>'+
			'</ExcelWorkbook>'+
			'<Styles>'+
				'<Style ss:ID="Default" ss:Name="Normal">'+
					'<Alignment ss:Vertical="Top" ss:Horizontal="Left" ss:WrapText="0"/>'+
				'</Style>'+
				'<Style ss:ID="th">'+
					'<Alignment ss:Vertical="Bottom"/>'+
					'<Font ss:Bold="1"/>'+
				'</Style>'+
			'</Styles>'+
			'<Worksheet ss:Name="'+(sheetname || sheetname === 0 ? sheetname : 'Sheet1')+'">'+
				'<Table>';
	
	elem = tableElem.children;
	for(e=0; e<elem.length; e++){
		if(elem[e].tagName === 'THEAD'){
			row = elem[e].children;
			for(r=0; r<row.length; r++){
				if(!headerComplete) headerRows++;
				addRow(row[r], 'th');
			}
		}
		else if(elem[e].tagName === 'TBODY'){
			headerComplete = true;
			row = elem[e].children;
			for(r=0; r<row.length; r++){
				addRow(row[r]);
			}
		}
		else if(elem[e].tagName === 'TR'){
			if(elem[e].children[0].tagName === 'TH'){
				if(!headerComplete) headerRows++;
				addRow(elem[e], 'th');
			}
			else{
				headerComplete = true;
				addRow(elem[e]);
			}
		}
	}
	
	xml +=		'</Table>'+
				'<WorksheetOptions xmlns="urn:schemas-microsoft-com:office:excel">'+
					'<Selected/>';
	if(headerRows){ xml +=
					'<FreezePanes/>'+
					'<FrozenNoSplit/>'+
					'<SplitHorizontal>'+headerRows+'</SplitHorizontal>'+
					'<TopRowBottomPane>1</TopRowBottomPane>'+
					'<ActivePane>2</ActivePane>'+
					'<Panes>'+
						'<Pane><Number>3</Number></Pane>'+
						'<Pane><Number>2</Number></Pane>'+
					'</Panes>';
	}
	xml +=			'<ProtectObjects>False</ProtectObjects>'+
					'<ProtectScenarios>False</ProtectScenarios>'+
				'</WorksheetOptions>';
	if(headerRows){ xml +=
				'<AutoFilter xmlns="urn:schemas-microsoft-com:office:excel" x:Range="R'+headerRows+'C1:R'+rowCount+'C'+columnCount+'"/>';
	}
	xml +=	'</Worksheet>'+
		'</Workbook>';
	
	return xml;
	
}