'use strict' module.exports = function isHeaderConditional (headers) { if (!headers || typeof headers !== 'object') { return false } const modifiers = [ 'if-modified-since', 'if-none-match', 'if-unmodified-since', 'if-match', 'if-range' ] return Object.keys(headers) .some(h => modifiers.indexOf(h.toLowerCase()) !== -1) }