Understandable Closures

closures.js

function buildFun(n){
  var res = [];
  for (var i = 0; i< n; i++){
    (function(number){
      res.push(function(){
        return number;
      });
    })(i)
  }
  return res;
}

// Craziness
return [...Array(n)].map((_, i) => () => i);

// ES6 (just beautiful)
res.push((i => () => i)(i));