lib/getCriticalDestination.js
function getCriticalDestination(rule, dest) {
  rule.walkDecls('critical-filename', function (decl) {
    dest = decl.value.replace(/['"]*/g, '');
    decl.remove();
  });
  return dest;
}
function getCriticalDestination(rule, dest) {
  rule.walkDecls('critical-filename', function (decl) {
    dest = decl.value.replace(/['"]*/g, '');
    decl.remove();
  });
  return dest;
}
function getCriticalDestination ( rule , dest ) { rule . walkDecls ( 'critical-filename' , function ( decl ) { dest = decl . value . replace ( / ['"]* / g , '' ) ; decl . remove ( ) ; } ) ; return dest ; }
Identify critical CSS destinations.

@param {object} rule PostCSS rule.
@param {string} Default output CSS file name.
@return {string} String corresponding to output destination.
Identify critical CSS destinations .