How do I toggle between displaying and hiding an element depending on a value selected from a drop down?

I am new to dev and am working on a little project of creating a worshipper counter app for my local mosque.

When the page loads, I want to show only the h1 and the drop down menu. Once an option selected, I want the counter app to display. I have written the function that will toggle the display using an onchange event. However, this is toggling between displaying and hiding no matter the option selected. I can’t seem to find how to display the counter when any value is selected from the dropdown. Please can someone point me in the right direction?

let count = 0
let saveEl = document.getElementById("save-el")
let countEl = document.getElementById("count-el")
let maxCount = document.getElementById("max")

function display() {
  let app = document.getElementById("counter")
  if (app.style.display === "none") {
    app.style.display = "block";
  } else {
    app.style.display = "none";
  }
  let value = document.getElementById("prayers").value;
  document.getElementById("prayerName").textContent = value


}

function increment() {
  count++
  countEl.textContent = count
  if (count >= 50) {
    console.log(count)
    maxCount.textContent = "MAX CAPACITY REACHED!"

  }
}

function subtract() {
  count--
  countEl.textContent = count
  if (count < 50) {
    maxCount.textContent = ""
  }
}

function save() {
  let countStr = count + " - "
  saveEl.textContent += countStr
  countEl.textContent = 0
  count = 0
  maxCount.textContent = ""
}

body {
  background-image: url("zakariyya mosque.png");
  background-size: cover;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  font-weight: bold;
  text-align: center;
}

h1 {
  margin-top: 10px;
  margin-bottom: 10px;
}

h2 {
  font-size: 50px;
  margin-top: 0;
  margin-bottom: 20px;
}

button {
  border: none;
  padding-top: 10px;
  padding-bottom: 10px;
  color: white;
  font-weight: bold;
  width: 200px;
  margin-bottom: 5px;
  border-radius: 5px;
}

#increment-btn {
  background: blue;
}

#subtract-btn {
  background: darkred;
}

#save-btn {
  background: darkgreen;
}

#max {
  color: crimson;
  animation: animate 1.5s linear infinite;
}

@keyframes animate {
  0% {
    opacity: 0;
  }
  /* 50% {
        opacity: 1;
    } */
  100% {
    opacity: 1;
  }
}

<h1>COVID19 MUSALLEE COUNTER:</h1>

<label for="prayers">Please select prayer:</label>
<select name="prayers" id="prayers" onchange="display()">
  <option></option>
  <option value="Fajr">Fajr</option>
  <option value="Zohar">Zohar</option>
  <option value="Asar">Asar</option>
  <option value="Magrib">Magrib</option>
  <option value="Isha">Isha</option>
</select>
<h3 id="prayerName"></h3>
<br><br>

<!-- COUNTER APP HTML -->
<div id="counter">
  <h2 id="count-el">0</h2>
  <h2 id="max"></h2>
  <button id="increment-btn" onclick="increment()">ADD</button>
  <button id="subtract-btn" onclick="subtract()">SUBTRACT</button>
  <button id="save-btn" onclick="save()">SAVE</button>
  <p id="save-el">Previous entries: </p>
  <p id="fajr">Fajr:</p>
  <p id="zohar">Zohar:</p>
  <p id="asar">Asar:</p>
  <p id="magrib">Magrib:</p>
  <p id="isha">Isha:</p>
</div>

Many thanks in advance! 🙂

Answer

You can take advantage of your “empty” option in the select so that display() can detect that:

let count = 0
let saveEl = document.getElementById("save-el")
let countEl = document.getElementById("count-el")
let maxCount = document.getElementById("max")

function display() {
  let app = document.getElementById("counter")
  if (document.getElementById("prayers").value){
    app.style.display = "block";
  } else {
    app.style.display = "none";
  }
  let value = document.getElementById("prayers").value;
  document.getElementById("prayerName").textContent = value


}

function increment() {
  count++
  countEl.textContent = count
  if (count >= 50) {
    console.log(count)
    maxCount.textContent = "MAX CAPACITY REACHED!"

  }
}

function subtract() {
  count--
  countEl.textContent = count
  if (count < 50) {
    maxCount.textContent = ""
  }
}

function save() {
  let countStr = count + " - "
  saveEl.textContent += countStr
  countEl.textContent = 0
  count = 0
  maxCount.textContent = ""
}

display()

body {
  background-image: url("zakariyya mosque.png");
  background-size: cover;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  font-weight: bold;
  text-align: center;
}

h1 {
  margin-top: 10px;
  margin-bottom: 10px;
}

h2 {
  font-size: 50px;
  margin-top: 0;
  margin-bottom: 20px;
}

button {
  border: none;
  padding-top: 10px;
  padding-bottom: 10px;
  color: white;
  font-weight: bold;
  width: 200px;
  margin-bottom: 5px;
  border-radius: 5px;
}

#increment-btn {
  background: blue;
}

#subtract-btn {
  background: darkred;
}

#save-btn {
  background: darkgreen;
}

#max {
  color: crimson;
  animation: animate 1.5s linear infinite;
}

@keyframes animate {
  0% {
    opacity: 0;
  }
  /* 50% {
        opacity: 1;
    } */
  100% {
    opacity: 1;
  }
}

<h1>COVID19 MUSALLEE COUNTER:</h1>

<label for="prayers">Please select prayer:</label>
<select name="prayers" id="prayers" onchange="display()">
  <option></option>
  <option value="Fajr">Fajr</option>
  <option value="Zohar">Zohar</option>
  <option value="Asar">Asar</option>
  <option value="Magrib">Magrib</option>
  <option value="Isha">Isha</option>
</select>
<h3 id="prayerName"></h3>
<br><br>

<!-- COUNTER APP HTML -->
<div id="counter">
  <h2 id="count-el">0</h2>
  <h2 id="max"></h2>
  <button id="increment-btn" onclick="increment()">ADD</button>
  <button id="subtract-btn" onclick="subtract()">SUBTRACT</button>
  <button id="save-btn" onclick="save()">SAVE</button>
  <p id="save-el">Previous entries: </p>
  <p id="fajr">Fajr:</p>
  <p id="zohar">Zohar:</p>
  <p id="asar">Asar:</p>
  <p id="magrib">Magrib:</p>
  <p id="isha">Isha:</p>
</div>