console 命令行工具 X clear

console

function addText() {
    let tag = document.querySelector('.container .box1')
    tag.innerText = tag.innerText + 1
}

  <div class="container">
    <div class="box box1"></div>
    <div class="box"></div>
    <div class="box"></div>
  </div>
  <button onclick="addText()">添加文字</button>

.container{display: flex;width: 120px;}
.box{flex-grow: 0;flex-shrink: 0;height:30px;background: red;margin: 3px;}