计时器 -0+ MVC模式

 <!-- 计时器 -->
<div id='count'></div>

js

// 计时器
// model
let data = {
    num: 0
}
// view
function calculate() {
    let str = `
    <button id='minus_Btn'>-</button>
    <label>${data.num}</label>
    <button id='add_Btn'>+</button>
    `
    count.innerHTML = str;
    minus_Btn.onclick = minusFunc
    add_Btn.onclick = addFunc
}
calculate()
// controller
function minusFunc() {
    if (data.num > 0) {
       data.num--; 
       calculate()
    }
}
function addFunc() {
    data.num++;
    calculate()
}