Check if an array value exists as part of the url
If you can use ES6 Features in your code, use a Set for constant lookup time:
const urlsToIgnore = new Set([
  'boldchat.com',
  'pinimg.com',
  'responsetap.com',
  'facebook.net',
  'dwin1.com',
  'bing.com',
  'google-analytics.com',
  'googletagmanager.com',
  'hotjar.com',
  'pinterest.com',
]);

// later
if (uslstoIgnore.has(event.request.url) { ... }

Otherwise, just use a simple object as a map:
const urlsToIgnore = {
  'boldchat.com': 1,
  'pinimg.com': 1,
  'responsetap.com': 1,
  'facebook.net': 1,
  'dwin1.com': 1,
  'bing.com': 1,
  'google-analytics.com': 1,
  'googletagmanager.com': 1,
  'hotjar.com': 1,
  'pinterest.com': 1,
};

// later
if (uslstoIgnore[event.request.url]) { ... }

Both these options offer constant time lookup, as opposed to the linear time of your current solution.
The actual performance gain depends on the size of the list with ignored items, but since this list can be added to, I'd opt for an O(1) lookup.