jquery focus out of focus

jQuery is a scripting language that allows developers to manipulate HTML and CSS by writing JavaScript code. It provides many convenient functions and methods to help developers enhance the interactivity of Web pages. Among them, focus and defocus are a common interactive operation. This article will explain the usage and implementation of focus and defocus in jQuery.

1. Focus

In Web development, focus refers to placing the mouse or keyboard cursor on the input box or other editable element to make it the currently "active" element. , you can enter data or perform other operations. In jQuery, the focus function can be achieved through the focus() method.

Syntax: $(selector).focus()

Among them, selector represents the element that needs to be focused, which can be a selector such as id, class, label, etc. For example, to focus on the element with the id of input, you can use the following code:

$("#input").focus();

or use the following code:

$ ("input#input").focus();

Or use the following code:

$("input[id='input']").focus();

In the above code, different selector methods are used to select the elements that need to be focused, but their effects are the same.

In actual development, sometimes it is necessary to automatically focus on an element when the page is loaded. This can be achieved by using jQuery's ready() method after the page is loaded.

The code is as follows:

$(document).ready(function(){

$("#input").focus();

});

In the above code, $( document).ready() method to wait for the page to load before performing the focus operation.

2. Defocus

Contrary to focus, defocus refers to moving the mouse or keyboard cursor away from the currently focused element so that it is no longer an "active" element. Then respond to input or operation. In jQuery, out-of-focus operation can be achieved through the blur() method.

Syntax: $(selector).blur()

Among them, selector represents the element that needs to be out of focus, which can be a selector such as id, class, label, etc. For example, to defocus the element whose id is input, you can use the following code:

$("#input").blur();

or use the following code:

$("input#input").blur();

Or use the following code:

$("input[id='input']").blur();

Similarly, defocusing can also be automatically achieved when the page is loaded. It can be achieved by using jQuery's ready() method after the page is loaded.

The code is as follows:

$(document).ready(function(){

$("#input").blur();

});

3. Application examples

Below, we use an application example to demonstrate the application effects of focus and defocus.

The code is as follows:

<title>jQuery聚焦失焦</title>

<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>

<style type="text/css">

    #input{

        width: 200px;

        height: 30px;

        font-size: 16px;

    }

    #result{

        margin-top: 20px;

        font-size: 16px;

    }

</style>

<script type="text/javascript">

    $(document).ready(function(){

        $("#input").focus(function(){

            $(this).css("background-color", "#f2f2f2");

        });

        $("#input").blur(function(){

            $(this).css("background-color", "#ffffff");

        });

        $("#btn").click(function(){

            $("#result").text($("#input").val());

        });

    });

</script>

< /head>

<input type="text" id="input" placeholder="请输入信息" />

<button id="btn">获取</button>

<div id="result">聚焦失焦效果演示</div>

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