Defer execution of function and preserve arguments. Aka thunkify

thunkify.js

// via https://www.oreilly.com/library/view/you-dont-know/9781491905197/ch04.html
function foo(x, y) {
  return x + y
}

function thunkify(fn) {
  var args = [].slice.call( arguments, 1 );
  return function(cb) {
      args.push( cb );
      return fn.apply( null, args );
  };
}

var fooThunk = thunkify(foo, 3, 4);

// later

fooThunk(function(sum) {
  console.log( sum );     // 7
});