## js实现倒计时同意按钮 >效果如图  >html代码 ``` <div class="box1"> <input type="button" id="btn" value="请仔细阅读协议(5)" disabled=true> //disabled=true 按钮无法点击 </div> ``` >js代码 ``` var oText = document.getElementById("text"); var oBtn = document.getElementById("btn"); var i = 4; /*setInterval(函数, 时间),实现定时器功能*/ var timer = setInterval(function(){ oBtn.value = "请仔细阅读协议("+i+")"; if(i == 0){ oBtn.disabled = false; clearInterval(timer); oBtn.value = "同意"; } i--; }, 1000) ```