read-cache 
Reads and caches the entire contents of a file until it is modified.
Install
$ npm i read-cache
Usage
// foo.js
var readCache = require('read-cache');
readCache('foo.js').then(function (contents) {
console.log(contents);
});
API
readCache(path[, encoding])
Returns a promise that resolves with the file's contents.
readCache.sync(path[, encoding])
Returns the content of the file.
readCache.get(path[, encoding])
Returns the content of cached file or null.
readCache.clear()
Clears the contents of the cache.
License
MIT © Bogdan Chadkin