write.js

/* require XLSX */
var XLSX = require('XLSX')

function datenum(v, date1904) {
	if(date1904) v+=1462;
	var epoch = Date.parse(v);
	return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);
}

function sheet_from_array_of_arrays(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;
}

/* original data */
var data = [[1,2,3],[true, false, null, "sheetjs"],["foo","bar",new Date("2014-02-19T14:30Z"), "0.3"], ["baz", null, "qux"]]
var ws_name = "SheetJS";

function Workbook() {
	if(!(this instanceof Workbook)) return new Workbook();
	this.SheetNames = [];
	this.Sheets = {};
}

var wb = new Workbook(), ws = sheet_from_array_of_arrays(data);

/* add worksheet to workbook */
wb.SheetNames.push(ws_name);
wb.Sheets[ws_name] = ws;

/* write file */
XLSX.writeFile(wb, 'test.xlsx');

I was getting corrupted files when using this code under a node environment. After a bit of messing around, I found the problem was the datenum function returns 12 decimal places which after writing out to a document, excel appears to not like.

Adding datenum(cell.v).toFixed(10) appears to solve this issue if anyone else comes across this problem.

I'm looking to giving style to the cells in node environment but I can't.
I have done styling cells in frontend like this inside sheet_from_array_of_arrays iteration

cell.s={
	fill:{
		fgColor:{ rgb: "CCFFCC" }
	},
	border: {
		top: {style: "medium", color: {rgb: "000"}},
		right: {style: "medium", color: {rgb: "000"}},
		bottom: {style: "medium", color: {rgb: "000"}},
		left: {style: "medium", color: {rgb: "000"}}
	}
}

but when trying to do the same on backend it doesn't work at all

In https://stackoverflow.com/a/42066961/8895274 is a way to generate xlsx with styles