<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../js/jquery-3.5.1.js"></script>
    <script>
        $(function () {
            //属性操作
            //设置属性，$().attr("属性","取值");
           var flag = true;
           $("#btn1").click(function () {
               if(flag)
               {
                   $("#pic").attr("src","img/2.png")
                       .attr("alt","2.png");
                   flag = false;
               }
               else
               {
                   $("#pic").attr("src","img/1.png")
                       .attr("alt","1.png");
                   flag = true;
               }
           });
        });

        /*
        在jQuery，设置属性有两种方式，
        一种是，设置一个属性，另外一个是设置多个属性
        语法：
        $().attr("属性","取值");

        $().attr({"属性1":"取值1","属性2":"取值2",......});
         */
    </script>
</head>
<body>
    <input type="button" id="btn1" value="修改"><br>
    <img id="pic" src="img/1.png" alt="1.png">
</body>
</html>