function enable(namespaces) {
		  exports.save(namespaces);

		  exports.names = [];
		  exports.skips = [];

		  var split = (typeof namespaces === 'string' ? namespaces : '').split(/[\s,]+/);
		  var len = split.length;

		  for (var i = 0; i < len; i++) {
		    if (!split[i]) continue; // ignore empty strings
		    namespaces = split[i].replace(/\*/g, '.*?');
		    if (namespaces[0] === '-') {
		      exports.skips.push(new RegExp('^' + namespaces.substr(1) + '$'));
		    } else {
		      exports.names.push(new RegExp('^' + namespaces + '$'));
		    }
		  }
		}
Check if the cache is fresh.

@return {Boolean}
@api private