expired

Calculate when HTTP responses expire from the cache headers

expired accepts HTTP headers as an argument and will return information on when the resource will expire.

Install

npm install --save expired

Usage

const expired = require('expired');

const headers = {
  'access-control-allow-origin': '*',
  'age': '0',
  'cache-control': 'public, max-age=300',
  'content-encoding': 'gzip',
  'content-type': 'application/json;charset=utf-8',
  'date': 'Fri, 23 Dec 2016 05:54:31 GMT',
  'last-modified': 'Fri, 23 Dec 2016 05:23:23 GMT',
  'vary': 'Accept-Encoding, User-Agent',
  'via': '1.1 varnish-v4'
};

new Date()
// Date('2016-12-23T05:54:31.000Z')

expired(headers)
// false

expired.in(headers)
// 300000

expired.on(headers)
// Date('2016-12-23T05:59:31.000Z')

delay(500000).then(() => {

  expired(headers)
  // true

  expired.in(headers)
  // -200000

  expired.on(headers)
  // Date('2016-12-23T05:59:31.000Z')

});

You can also pass headers in as raw text:

const expired = require('expired');

const headers = `
Access-Control-Allow-Origin: *
Age: 0
Cache-Control: public, max-age=300
Content-Encoding: gzip
Content-Type: application/json;charset=utf-8
Date: Fri, 23 Dec 2016 05:54:31 GMT
Last-Modified: Fri, 23 Dec 2016 05:23:23 GMT
Vary: Accept-Encoding, User-Agent
Via: 1.1 varnish-v4`;

expired(headers)
// false

API

expired(headers)

Returns a boolean relating to whether the resource has expired or not. true means it's expired, false means it's fresh.

expired.in(headers)

Returns the amount of milliseconds until the resource will expire. If the resource has already expired it will return a negative integer.

expired.on(headers)

Returns a JavaScript Date object for the date the resource will expire.

License

MIT © Luke Childs