JSFiddle - React, Tailwind, and code Playground

HTML

<form name="myForm" id="myForm">
    <div id="ctrl-group">
        <div name="myInput">
            <label>Input 1</label>
            <input type="text" name="myInputA" />
            <input type="text" name="myInputB" />
            <input type="text" name="myInputC" />
        </div>
    </div>
    <br />
    <input type="button" value="add new input" id="addInput" />
    <input type="button" value="delete input" id="deleteInput" />
    <input type="button" value="Show all value" id="showVal" />
</form>

JavaScript

//get the form element
var myForm =  document.getElementById("myForm"),
    //gets the div-container of the inputs
    ctrlGroup = document.getElementById("ctrl-group"),
    //get the add button
    addButton = document.getElementById("addInput"),
    //get the delete button
    deleteButton = document.getElementById("deleteInput"),
    //get the show value button
    showButton = document.getElementById("showVal");

// adds a new input when "add new input" button is clicked
addButton.onclick = function(){
    var newInput = document.createElement("div");
    newInput.setAttribute("name","myInput");
    newInput.innerHTML = '<label>Input ' + (ctrlGroup.childElementCount + 1) + '</label><input type="text" name="myInputA" /><input type="text" name="myInputB" /><input type="text" name="myInputC" />';
    ctrlGroup.appendChild(newInput);
};

//delete the last input when "delete input" is clicked
deleteButton.onclick = function(){
    ctrlGroup.removeChild(ctrlGroup.lastElementChild);
};

//show the value of the elements when clicked
showButton.onclick = function(){
    var inputA = document.getElementsByName("myInputA"),
        inputB = document.getElementsByName("myInputB"),
        inputC = document.getElementsByName("myInputC"),
        inputStr = "",
        i=0,
        len=ctrlGroup.childElementCount;
    for(;i<len;i++){
        inputStr += ("INPUT" + i +": " + inputA[i].value + " " + inputB[i].value + " " + inputC[i].value + "\n");
    }
    alert(inputStr);
};