Font Audit Utility

audit.js

console.log( 'FontAudit', Array.from( document.querySelectorAll( '*' ) ).flatMap( function ( el ) {
  return [ [ el, getComputedStyle( el ) ], [ el, getComputedStyle( el, ':before' ) ], [ el, getComputedStyle( el, ':after' ) ] ];
} ).reduce( function ( fs, cst ) {
  var el = cst[ 0 ];
  var cs = cst[ 1 ];
  var ff = cs[ 'font-family' ];
  var fw = cs[ 'font-weight' ];
  fs[ ff ] = fs[ ff ] || {};
  fs[ ff ][ fw ] = fs[ ff ][ fw ] || new Set();
  fs[ ff ][ fw ].add( el );
  return fs;
}, {} ) );

Useful as a bookmarklet