RunKit + npm: kiper

const kiper = require('kiper'); // somewhere keep an asset kiper.keep('foo', 'bar'); // somewhere you got it back let value = kiper.get('foo'); console.log('Got from kiper: ' + value);

console.log('Observe an object and notify on value of the item is changed'); // keep an asset here let baz = kiper.keep('baz', { gold: 1000 }); kiper.watch('baz', (obj, oldVal, propkey, type) => { if (type === 'update') { console.log('lost one gold: ' + (obj[propkey] - oldVal)); } else if (type === 'add') { console.log('new prop should be added: ' + (obj['silver'])); } else if (type === 'delete') { console.log('baz should be undefined after delete: ' + (typeof obj['gold'])); } else { console.log('do not know change type: ' + type); } }); // baz is going to change somewhere baz.gold = 999 baz.silver = 1000 delete baz.gold

let foobar = kiper.keep('foobar', { gold: 1000, owner: { name: 'Bill Gate', age: 61 } }); // deep watching ... kiper.watch('foobar', true, (obj, oldval, propkey, type) => { console.log('robber has gold:', obj, oldval) }); // the owner has lost his gold foobar.owner.name = 'robber'