var index;

​

for(index = 0 ; index < 5 ; index++) {

  setTimeout(function() {

    console.log("with side effect", index);

  }, 1000);

}

​

function recreateLocalScope(localIndex) {

  return function() {

      console.log("no side effect", localIndex);

  };

}

​

for(index = 0 ; index < 5 ; index++) {

  setTimeout(recreateLocalScope(index), 1000);

}

​

​