jquery package function usage-Front-end Q&A-php.cn

jQuery is a widely used JavaScript library that can help developers greatly reduce the amount of code in DOM operations, event handling, and animation effects. Encapsulated functions are an important feature in the jQuery library. Commonly used code logic can be encapsulated in a function, and the function can be called directly when needed to improve code reusability and development efficiency. This article will introduce the usage of jQuery wrapper functions and how to write high-quality wrapper functions.

1. Why encapsulate functions

Encapsulating functions is one of the best ways to improve development efficiency and code reusability. When we use jQuery for DOM operations or event processing, we often need to write the same or similar code multiple times, which will cause code redundancy and inconvenient maintenance. By encapsulating commonly used code logic into a function, we can directly call the function when needed, greatly reducing repeated code and improving code reusability. In addition, encapsulating functions can also improve the readability and maintainability of the code, making the code more concise and clear.

2. The basic syntax of the encapsulated function

In jQuery, the basic syntax of the encapsulated function is:

$.fn.extend({
    functionName: function (parameters) {
        // function body
    }
});

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Among them, $.fn is a jQuery object, indicating that all DOM elements can call this function. extend()The method is a method used to extend objects in jQuery. It can extend the original jQuery object or create a new jQuery object. functionName is our custom function name, parameters is the parameters that the function needs to accept.

3. Application of encapsulated functions

The following takes encapsulating a commonly used form validation function as an example to introduce how to use jQuery to encapsulate functions.

1. Implement form verification logic

function checkInput(str, pattern) {
    var regExp = new RegExp(pattern);
    return regExp.test(str);
}

function validateForm() {
    var userName = $("#userName").val(),
        userPhone = $("#userPhone").val(),
        userEmail = $("#userEmail").val();

    // 验证用户名
    if (checkInput(userName, "^\w{5,20}$") === false) {
        alert("用户名格式不正确");
        return false;
    }

    // 验证电话号码
    if (checkInput(userPhone, "^\d{11}$") === false) {
        alert("电话号码格式不正确");
        return false;
    }

    // 验证邮箱地址
    if (checkInput(userEmail, "^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+$") === false) {
        alert("邮箱地址格式不正确");
        return false;
    }

    return true;
}

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The above code implements a simple form verification logic, including verification of three input boxes: the user name requires 5 to 20 letters, numbers or underscores ;The phone number is 11 digits; the email address is in standard format. In this code, the checkInput() function is used to verify whether it conforms to the regular expression format, and the validateForm() function is responsible for verifying whether the data in each input box in the form is legal.

2. Encapsulate the function into a plug-in

In order to improve code reusability, we can encapsulate the above form validation function into a jQuery plug-in to achieve the following steps:

(1) Use the jQuery.fn.extend() function to extend the jQuery object and create a new plug-in:

$.fn.checkForm = function () {
    var input = $(this), // 获取当前表单的元素
        userName = input.find("#userName").val(),
        userPhone = input.find("#userPhone").val(),
        userEmail = input.find("#userEmail").val();

    // 验证用户名
    if (checkInput(userName, "^\w{5,20}$") === false) {
        alert("用户名格式不正确");
        return false;
    }

    // 验证电话号码
    if (checkInput(userPhone, "^\d{11}$") === false) {
        alert("电话号码格式不正确");
        return false;
    }

    // 验证邮箱地址
    if (checkInput(userEmail, "^[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+$") === false) {
        alert("邮箱地址格式不正确");
        return false;
    }

    return true;
}

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This function is a closure, passed input The variable gets the elements of the current form and then performs the validation operation.

(2) Call the plug-in on the page:

<form id="userForm" action="submitForm.php" method="post">
    <input id="userName" type="text" placeholder="请输入用户名">
    <input id="userPhone" type="text" placeholder="请输入电话号码">
    <input id="userEmail" type="text" placeholder="请输入邮箱地址">
    <button id="submit">提交</button>
</form>

<script>
    $("#submit").on("click", function () {
        if ($("#userForm").checkForm() === false) {
            return false;
        }
    });
</script>

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When the form is submitted, we can directly call the plug-in for verification operations. Note that this plug-in can only be used on form elements and must contain input boxes with id being userName, userPhone and userEmail.

4. Write high-quality encapsulated functions

Above we have introduced the basic syntax and application of jQuery encapsulated functions. Next, we will focus on how to write high-quality encapsulated functions.

1. Try to simplify function functions as much as possible

The purpose of encapsulating functions is to improve code reusability and development efficiency, so we should try to simplify function functions as much as possible to avoid implementing too many functions in one function function, which facilitates code reuse and maintenance. For example, for the form validation function above, we can abstract the checkInput() function into a separate tool function, and then encapsulate the validation logic into the form validation function to make the function clearer and simpler.

2. Pay attention to the scalability and compatibility of the function

When encapsulating functions, we should pay attention to the scalability and compatibility of the function. When implementing function logic, we should take into account future demand changes and set aside corresponding extension interfaces for functions to facilitate expansion and adjustment when needed. In addition, we should also try to consider compatibility issues to ensure that the function can work properly on different browsers and devices.

3. Follow code specifications and best practices

Encapsulated functions should follow unified code specifications and best practices to improve code readability and maintainability. When writing functions, we should pay attention to naming conventions, code indentation, comments, etc. to make the code structure clear, easy to read and maintain.

Summary

jQuery encapsulated function is an important tool to improve development efficiency and code reusability. In actual development, we should reasonably use jQuery encapsulation functions to encapsulate commonly used code logic into a function to make the code more concise, easy to read and easy to maintain. At the same time, we must also pay attention to the scalability and compatibility of functions, follow unified code specifications and best practices, and lay a good foundation for subsequent code development and maintenance.

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