jquery plugin private method

jQuery is a very popular JavaScript library that easily provides web developers with various features and tools. Among them, plug-ins are a major feature of jQuery. They can add more functions and operations to jQuery. This article will introduce the private methods in jQuery plug-ins, which are very important in plug-in development.

1. What is a jQuery plug-in?

Before introducing private methods in detail, we need to understand what a jQuery plug-in is. jQuery plug-in is a way to extend the functionality of the jQuery library, which can add various practical effects and functions to the website. For example, image carousel, form validation, pop-up windows, etc.

There are two types of jQuery plug-ins, one is global plug-in and the other is local plug-in. Global plugins are methods that are extended under the jQuery namespace and can be used throughout the application. Local plug-ins are methods that are extended under the namespace of a specific element and can only be used in the specified element.

2. How to write jQuery plug-in?

Writing a jQuery plug-in is not complicated, you just need to follow some specifications. The following are the basic specifications for writing jQuery plug-ins:

1. Use functions to define plug-ins, for example:

(function ($) {
   //插件代码
})(jQuery);

2. Define default options and parameters in the plug-in, for example ：

$.fn.myPlugin = function (options) {
  var settings = $.extend({
      //默认参数
  }, options);
  //插件代码
};

3. The plug-in should return a jQuery object to facilitate chain calls.

$.fn.myPlugin = function (options) {
  //插件代码
  return this;
};

3. What is a private method?

In jQuery plug-ins, private methods refer to functions defined in the plug-in and can only be used inside the plug-in. It is equivalent to the internal method of the plug-in and will not be called externally. Private methods are often used to perform some repetitive or complex tasks, breaking down complex and time-consuming tasks into multiple small, easy-to-maintain methods.

When writing plug-ins, we can use private methods to implement some more complex functions. First, we need to define private methods in the plug-in code, for example:

$.fn.myPlugin = function (options) {
  var settings = $.extend({
      //默认参数
  }, options);

  function privateMethod() {
      //私有方法代码
  }

  //插件代码
  return this;
};

Then, we can use these private methods in the plug-in to complete certain tasks. Since these private methods can only be used inside the plug-in, they do not need to deal with parameters and return values ​​like public methods, making the plug-in code more concise and easier to maintain.

4. Example of using private methods

The following is a simple example that demonstrates how to use private methods in a plug-in. In this example, we convert the text entered in the text box to uppercase letters. However, to demonstrate the usefulness of private methods, we split the uppercase conversion process into two private methods.

$.fn.myPlugin = function (options) {
  var settings = $.extend({
      //默认参数
  }, options);

  function toUpperCase(str) {
      return str.toUpperCase();
  }

  function transformText(elem) {
      var text = elem.val();
      var uppercase = toUpperCase(text);
      elem.val(uppercase);
  }

  return this.each(function () {
      var input = $(this);
      input.on('blur', function () {
          transformText(input);
      });
  });
};

In this example, we define two private methods: toUpperCase() and transformText(). Among them, the toUpperCase() method converts the input text to uppercase letters, and the transfromText() method will get the value in the input text box, then convert it to uppercase letters and reassign it to the text box.

At the end of the plug-in, we will use the each() method to traverse all text boxes and bind the blur event to them. When the user leaves the text box, the plug-in will automatically execute the transformText() method to complete the conversion of uppercase letters.

5. Summary

jQuery plug-in is a very popular way to add various practical functions to the website. In the development of plug-ins, private methods are very important, as they can break down complex and time-consuming tasks into multiple small, easy-to-maintain methods. Through the use of private methods, the plug-in code can be made simpler and easier to maintain, and play a greater role in actual development.

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