How to set cell width when export .xlsx files with js-xlsx

I found a snippet the the write test here https://github.com/SheetJS/js-xlsx/blob/master/tests/write.js#L14-L19

For quick reference, where ws is your worksheet.

var wscols = [
    {wch:6},
    {wch:7},
    {wch:10},
    {wch:20}
];

ws['!cols'] = wscols;