main.js

(function(){
    var counter = 0;
    var addBtn = document.querySelector("#addBtn");
    var minBtn = document.querySelector("#minBtn");
    var friends = document.querySelector("#friends");

    addBtn.addEventListener("click", createInput);
    minBtn.addEventListener("click", removeInput);

    createInput();

    function createInput() {
        console.log("You added a friend!");
        counter++;
        console.log("counter", counter);
        if(counter > 1 && counter < 10){
            minBtn.style.display = "inline";
        }else if(counter == 10){
            console.log("Hide display button!");
            addBtn.style.display = "none";
        }
//
//        if(counter >= 1 && counter < 10){
//
//        }

        var tf_friend = document.createElement("input");
        tf_friend.setAttribute("type", "email");
        tf_friend.id = "tf_friend" + counter;
        tf_friend.name = "emails[]";

        var label = document.createElement("label");
        label.innerHTML = "Friend's Email:";
        label.setAttribute("for", tf_friend.id);

        var hiddenInput = document.createElement("input");
        hiddenInput.setAttribute("type", "hidden");
        hiddenInput.id = "tf_ref_id" + counter;
        hiddenInput.name = "ref_ids[]";
        hiddenInput.value = ~~(Math.random()*(9999999-1000000+1)+1000000);
        console.log("Ref ID: " + hiddenInput.value);

        friends.insertBefore(label, addBtn);
        friends.insertBefore(tf_friend, addBtn);
        friends.insertBefore(hiddenInput, addBtn);
    }

    function removeInput() {
        console.log("You removed a friend!");
        counter--;

        if(counter == 1){
            minBtn.style.display = "none";
        }

        if(counter == 9){
            addBtn.style.display = "inline";
        }

        friends.removeChild(friends.children[friends.children.length - 3]);   //[friends.children.length - 3]
        friends.removeChild(friends.children[friends.children.length - 3]);
        friends.removeChild(friends.children[friends.children.length - 3]);
    }
})();