加号和减号按钮(Javascript)

// HTML代码
<button id="plusBtn">+</button>
<span id="count">0</span>
<button id="minusBtn">-</button>

// JavaScript代码
var count = 0;
var plusBtn = document.getElementById("plusBtn");
var minusBtn = document.getElementById("minusBtn");
var countSpan = document.getElementById("count");

plusBtn.addEventListener("click", function() {
  count++;
  countSpan.textContent = count;
});

minusBtn.addEventListener("click", function() {
  if (count > 0) {
    count--;
    countSpan.textContent = count;
  }
});