This bit of JavaScript regex will parse the interfaces out of an entire Cisco IOS config!

Cisco_IOS_Regex_hints.js

var config = fs.readFileSync('configFile.txt').toString();

var interfaces = config.match(/interface .+[\r]*\n [\s\S]+?[^\ ]!/g);

console.log(interfaces):
/*
[
  "interface Vlan1\n description ...\n!",
  "interface Vlan2\n description ...\n!",
  ...
]
*/