Javascript/TypeScript – Can I add class properties from an array?

Thank you for the help in advance. I am working in TypeScript, I’d assume any JS solution also works. I’d like to make something like this:

class ExcelData {
  'Id 1': items[0].id,
  'Quantity 1': items[0].quantity,
  'Id 2': items[1].id,
  'Quantity 2': items[1].quantity
  //...
  'Id 40': items[39].id,
  'Quantity 40': items[39].quantity,
}

I am trying to use it with the ‘xlsx’ module to export project data into an Excel sheet. It is necessary for this module that it is a class, rather than several arrays. I could type it out manually, but there is 7 properties for every item and this would be very ugly code. It is also possible that I am later asked to add more items.
If it were Python, I could do something like this bc classes and dictionaries are different things:

excel_data = {}
for i in range (40):
  excel_data['Id '+ str(i)] = items[i].id
  excel_data['Quantity '+ str(i)] = items[i].quantity

What is a Typescript alternative?

Thanks!