Loading local JSON file
I had the same need (to test my angularjs app), and the only way I found is to use require.js:
var json = require('./data.json'); //(with path)
note: the file is loaded once, further calls will use the cache.
More on reading files with nodejs: http://docs.nodejitsu.com/articles/file-system/how-to-read-files-in-nodejs
In a more modern way, you can now use the Fetch API:
fetch("test.json") .then(response => response.json()) .then(json => console.log(json));
All modern browsers support Fetch API. (Internet Explorer doesn't, but Edge does!)