Create an element inside the created element

Question

I want to write a function that when I click, create a DIV element inside a created DIV element. Below is my code.

The result I want to see is that one black div block contains a blue div block and display five times. But the result is five blue div blocks all in one black div block. Can someone tell me why?

function createDiv() {
  for (let i = 0; i < 5; i++) {
    let newDiv = document.createElement("div");
    let myDiv = document.querySelector(".test");
    myDiv.appendChild(newDiv);
    newDiv.className = "new";

    let newDiv1 = document.createElement("div");
    let myDiv1 = document.querySelector(".new");
    myDiv1.appendChild(newDiv1);
    newDiv1.className = "inside";
  }
}

.test {
  width: 800px;
  height: 300px;
  background-color: aquamarine;
}

.new {
  width: 100px;
  height: 100px;
  background-color: black;
  display: inline-block;
}

.inside {
  width: 50px;
  height: 50px;
  margin: 0px auto;
  background-color: blue;
  display: inline-block;
}

<div class="container">
  <button class="btn" id="btn" onclick="createDiv()">click</button>
  <div class="test" id="test">
  </div>
</div>

Answer 1

The issue is because in each iteration of the loop you select all the .new elements in the DOM - even those which were created in previous loop iterations.

To fix this you should use the newDiv reference which was created within the current iteration:

let myDiv = document.querySelector(".test");

function createDiv() {
  for (let i = 0; i < 5; i++) {
    let newDiv = document.createElement("div");
    myDiv.appendChild(newDiv);
    newDiv.className = "new";

    let newDiv1 = document.createElement("div");
    newDiv.appendChild(newDiv1);
    newDiv1.className = "inside";
  }
}

.test {
  width: 800px;
  height: 300px;
  background-color: aquamarine;
}

.new {
  width: 100px;
  height: 100px;
  background-color: black;
  display: inline-block;
}

.inside {
  width: 50px;
  height: 50px;
  margin: 0px auto;
  background-color: blue;
  display: inline-block;
}

<div class="container">
  <button class="btn" id="btn" onclick="createDiv()">click</button>
  <div class="test" id="test">
  </div>
</div>