Add element AFTER another.js

/* Insert Login Button inside regform block */
function insertAfter(referenceNode, newNode) {
  referenceNode.parentNode.insertBefore(newNode, referenceNode.nextSibling);
}

var mibileLoginBtn = document.createElement("div");
mibileLoginBtn.innerHTML = "Log In";
mibileLoginBtn.classList.add('btn', 'login-btn-mobile');
var multiButtonsForm = document.querySelector(".main-section .reg-form-block");
var nextButton = multiButtonsForm.querySelector('.next-btn');
insertAfter(nextButton, mibileLoginBtn);