HTML:
<span class="rbx-text-navbar-right text-header" id="nav-robux-amount">11</span>
CODE:
element = document.getElementById("nav-robux-amount")
if (element){
window.alert(element.value)
}
window.alert shows that the value of element is undefined
The .value property only exists on inputs.
The 'element' isn't a constant variable.
If you want to get the content, you can do the following:
const element = document.getElementById("nav-robux-amount");
if (element) window.alert(element.textContent)
Note: innerHTML is not as good as textContent, as it is vulnerable to attacks.