無法在 javascript 中使用 + 運算符增加價值

Question

每當單擊按鈕時，我都會嘗試將值增加 1。 我什至通過使用parseInt()將值轉換為 int，因為它不斷增加計數器而不是值。

當我單擊值為 1 的按鈕時。單擊時我的預期結果將是 2 3 4 5 6 7 等等...

<div id="move_left_right">
 <button class="btn" value=1 onclick="counter()" id="left"><<</button>
</div>

function counter()
{
    let valueIs  = document.getElementById('left').value;
    let conversion = parseInt(valueIs);
    let sum = conversion + 1;
    localStorage.setItem("getSum" , sum);
}
//getting value of sum outside function using local storage
let x = localStorage.getItem("getSum")
console.log(x);
//setting value to left as 2 
document.getElementById('left').value= x;

//now value is 2 when button is pressed i want the value to be 3 4 5 etc

Answer 1

我編輯了你的功能，現在它更新了按鈕的值+它存儲到本地存儲中：

function counter() {
    let btn =  document.getElementById('left')
    let value = parseInt(btn.value);
    let sum = value + 1;
    localStorage.setItem("getSum" , sum);
    btn.value = sum;

    console.log(sum);
    console.log(typeof(sum));
}