javascript - 在javascript类中获取文档计数列表

Question

This is the html

<ul id="List">
   <li><h2>Numeros Primos</h2></li>
   <li>Hello World</li>
   <li>Not Work</li>
</ul>
<p id="count"></p>

---

This is the javascript

class List {
        static Restart() {
            document.getElementById("List").innerHTML = "<li><h2>Numeros Primos</h2></li>";
        }
        static add(Number) {
            document.getElementById("List").innerHTML += "<li>" + Number + "</li>"
        }
        get count() {
            return document.getElementById("List").childElementCount
        }
    }

    document.getElementById("count").innerHTML = List.count;
    // return undefined

PROBLEM

I can't get count number in the list

it return "undefined"

Answer 1

使计数静态 :)

class List {
        static Restart() {
            document.getElementById("List").innerHTML = "<li><h2>Numeros Primos</h2></li>";
        }
        static add(Number) {
            document.getElementById("List").innerHTML = document.getElementById("List").innerHTML + "<li>" + Number + "</li>"
        }
        static get count() {
            return document.getElementById("List").childElementCount;
        }
    }

    document.getElementById("count").innerHTML = List.count;

<ul id="List">
   <li><h2>Numeros Primos</h2></li>
   <li>Hello World</li>
   <li>Not Work</li>
</ul>
<p id="count"></p>