<!-- 有个小院-兴趣编程 --><main>  <div class="set">    <h2>有个小院-计数器</h2>    <span class="value">0</span>    <div>      <button class="btn btn-danger decrease"><i class="fa fa-minus" aria-hidden="true"></i> </button>      <button class="btn btn-secondary reset">重置</button>      <button class="btn btn-success increase"><i class="fa fa-plus" aria-hidden="true"></i> </button>    </div>  </div></main>

//有个小院-兴趣编程let num=0;const value=document.querySelector(".value");const btns = document.querySelectorAll(".btn");btns.forEach((btn)=>{  btn.addEventListener("click",(e)=>{    const styles=e.currentTarget.classList;    if(styles.contains("decrease")){      num--;    }else if(styles.contains("increase")){      num++;    }else{      num=0;    }    value.textContent=num;      if(num>0){      value.style.color="green";      }else if(num<0){      value.style.color="red";      }else{      value.style.color="black";      }      });      });