The converter from typeface.js
uses server-side perl scripts and the sources are on Launchpad.
Here is an extract from its README:
use TypefaceJS;
my $typeface = TypefaceJS::new->( input_filename => "truetype_font.ttf",
unicode_range_names => ['Basic Latin', 'Latin-1 Supplement'], );
$typeface->write_file( output_filename => 'font.typeface.js' );