lovecoding
/
class


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      * {
        margin: 0;
        padding: 0;
      }
      .box {
        width: 200px;
        height: 200px;
        background: #ff0;
      }
    </style>
  </head>
  <body>
    <div class="box"></div>
    <br /><br />
    <button id="btn1">放大</button>
    <br />
    <br />
    <button id="btn2">缩小</button>
    <script>
      var box = document.querySelector(".box");
      var btn1 = document.getElementById("btn1");
      var btn2 = document.getElementById("btn2");
      btn1.onclick = function () {
        var timer = setInterval(function () {
          box.style.width = box.offsetWidth + 5 + "px";
          if (box.offsetWidth >= 400) {
            clearInterval(timer);
          }
        }, 100);
      };
      btn2.onclick = function () {
        var timer = setInterval(function(){
            box.style.width = box.offsetWidth - 5 + "px";
            if(box.offsetWidth <= 200) {
                clearInterval(timer);
            }
        },100)
      }
    </script>
  </body>
</html>