how do I add to a number value in html through javascript

Question

I tried

HTML:
<br> <span id="myspan">0</span>
Javascript:
button.addEventListener("click"), function() { document.getElementById("myspan").textContent=("+-1"); };

but it didn't seem to be working and nothing seemed to cover this. I was trying to make a click counter for fun and the button click listener, I don't know if it worked.

Javascript:
button.addEventListener("click"), function() { document.getElementById("myspan").textContent=("+-1"); };

Answer 1

Your addEventListener isn't correct.

button.addEventListener("click"), function() { should actually be button.addEventListener("click", function() {}) since the function needs to be within the parentheses.`

const button = document.getElementById('button');
const span = document.getElementById("myspan");
button.addEventListener("click", function() {  
  let val = parseInt(span.innerText || '') || 0;
  val++;
  span.innerText= val;
});

https://codepen.io/dirtyd77/pen/KKErYRy