jQuery focusin()方法

jQuery focusin()是一个内置的方法，用于获得选定元素的焦点。

语法:

$(selector).focusin(function);

参数：它接受一个可选的参数 “函数”，以获得对选定元素的关注。

jQuery例子显示focusin()方法的工作：
例子1：在下面的代码中，参数函数被传递。

<!DOCTYPE html>
<html>
  
<head>
    <script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js">
    </script>
  
    <!-- jQuery code to show the working of this method -->
    <script>
         $(document).ready(function () {$ ("div").focusin(function () {
                $(this).css("background-color", "green");
            });
        });
    </script>
  
    <style>
        div {
            border: 2px solid black;
            width: 50%;
            padding: 20px;
        }
  
        input {
            padding: 5px;
            margin: 10px;
        }
    </style>
</head>
  
<body>
    <!-- click inside the field focusin will take place -->
    <div>
        Enter name:
        <input type="text">
        <br>
    </div>
</body>
  
</html>

输出:

jQuery focusin()方法

例子2：在下面的代码中，没有传递任何参数。

<!DOCTYPE html>
<html>
  
<head>
    <script src=
"https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js">
    </script>
  
    <!-- jQuery code to show the working of this method -->
    <script>
         $(document).ready(function () {$ ("#foc").click(function () {
                $(this).focusin().css("background-color", "lightgreen");
            });
        });
    </script>
  
    <style>
        div {
            border: 2px solid black;
            width: 50%;
            padding: 20px;
        }
  
        input {
            padding: 5px;
            margin: 10px;
        }
    </style>
</head>
  
<body>
    <!-- click inside the field focusin will take place and
    background color becomes change -->
    <div>
        Enter name:
        <input id="foc" type="text">
        <br>
    </div>
</body>
  
</html>

输出:

jQuery focusin()方法