Create a XLS file dynamically with XLSX in Angular - xlsx

Question

I'm creating a pickList where there's a list of attributes that the user can choose to create its own personal report. But I'm having quite some trouble on creating this XLS, because of two things.
First my XLSX.utils.json_to_sheet is ignoring blank fields (""), and I can't have that because it will desorganize the whole report.
Second: because its a dynamic xls, I can't know how many columns there will be created...
Here's what I've done so far, regarding the xls creation part:
exportTable() {
this.createObjectWithColumnsSelected(); //ignore this, i'm only creating a reference object based on the user columns choices
this.manipulateExportableData(); //manipulating the whole table data, to be formated accordly the reference object
const worksheet = XLSX.utils.json_to_sheet(this.customersTable);
this.changeHeaderWorksheet(worksheet);
}
converte(): string[] {
const alph = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ";
return alph.split('');
}
changeHeaderWorksheet(worksheet: WorkSheet): void {
const alphabet = this.converte();
for (let i = 0; i < this.cols.length; i++) {
if (i >= 26){
console.log(this.cols[i].header);
worksheet[`A${alphabet[i]}1`] = this.cols[i].header;// I think this is quite wrong
}else{
console.log(this.cols[i].header);
worksheet[`${alphabet[i]}1`] = this.cols[i].header; //I think this is quite wrong
}
}
}