halfexpired-lru

lru-cache where get accepts an optional "fill" callback. A fill callback would be used to populate a value in the background before it is really expired. set also supports ttl per key.

example

var cache = require('halfexpired-lru');

cache.set('a',1);

cache.get('a',function(err,key,value,ttl){
  if(err == 'halfexpired') {
    // stop it from being half expired.
    cache.set(key,value,ttl);
    request(url,function(err,data){
      if(err) console.log('that flakey api failed again! good thing my value is not completely expired ;)');
      else cache.set(key,value,ttl);
    })
  }
});