Formatting a number to have commas at every 1000 factor

Just use the number (decimal) pipe instead.

To give an example:

{{ '1234567' | number:'1.0':'en-US' }}

will produce output 1,234,567.

If you do not change the default locale (by calling registerLocaleData() or providing LOCALE_ID), then simple {{'1234567' | number}} will work as well.