How to calculate the amount for the number of products in javascript?

Question

JavaScript

Good day!
There is such a code

<td>
<input type="text" name="count-item" id="count" value="1">
 </td>
<span id="cost">52.5</span>
<span id="result"></span>

tell me the code so that when the number in Input (Count) changes, it takes the value and multiplies it by span (Cost) and displays the result in span (result)
Thank you!
PS If you can, then still advise a good book on javascript. I have mastered PHP HTML CSS and actively work, but I am practically not familiar with JS.

Answer 1

var cost = document.getElementById('cost');
var count = document.getElementById('count');
var result = document.getElementById('result');

count.addEventListener('change', function() {
  result.textContent = parseInt(count.value, 10) * parseFloat(cost.textContent);
});