console 命令行工具 X clear

console

$(function(){
  var count = 0;
  $('.btn').on('click',function(){
    count ++;
  });
});

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8" />
  <title>Document</title>
</head>
<body>
  <input type="button" value='button' class="btn"/>
</body>
</html>