jQuery defines plug-in method_jquery

Some WEB developers will reference a JQuery class library, and then write $("#"), $(".") on the web page. After writing for a few years, they will tell others that they are very familiar with JQuery. I used to be such a person, but it wasn't until a technical exchange in the company that I changed my view of myself.

When extending jquery. The core methods are the following two:

$.extend(object) can be understood as adding a static method to jquery

$.fn.extend(object) can be understood as adding a method to the jquery instance

$.extend(object)

Example:

/* $.extend 定义与调用
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
$.extend({ fun: function () { alert("执行方法一"); } });//定义
$.fun();//调用
$.fn.extentd(object)
/* $.fn.extend 定义与调用
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
$.fn.extend({ fun: function () { alert("执行方法"); } });
$(this).fun();
//等同于
$.fn.fun = function () { alert("执行方法三"); }
$(this).fun();

Define the basic structure of jquery plugin

1． Define scope:

Define a private scope for the plugin. External code cannot directly access the inside of the plug-in. The internal code of the plug-in is not subject to external interference, nor does it pollute global variables.

  //step 定义JQuery的作用域
(function ($) {
})(jQuery);

2. Add extension methods to the plug-in:

//step01 定义JQuery的作用域
(function ($) {
  //step02 插件的扩展方法名称
  $.fn.easySlider = function (options) {
    
  }
})(jQuery);

3. Set default value:

//step 定义JQuery的作用域
(function ($) {
  //step-a 插件的默认值属性
  var defaults = {
    prevId: ‘prevBtn‘,
    prevText: ‘Previous‘,
    nextId: ‘nextBtn‘,
    nextText: ‘Next‘
    //……
  };
  //step 插件的扩展方法名称
  $.fn.easySlider = function (options) {
    //step-b 合并用户自定义属性，默认属性
    var options = $.extend(defaults, options);
  }
})(jQuery);

Among them: var options = $.extend(defaults, options) means. Indicates that options overrides the value of defaults and assigns the value to options.
In the plug-in environment, it means that the value set by the user overrides the default value of the plug-in; if the user does not set the attribute with a default value, the default value of the plug-in is still retained.

4. Support jquery selector:

 //step 定义JQuery的作用域
(function ($) {
  //step-a 插件的默认值属性
  var defaults = {
    prevId: ‘prevBtn‘,
    prevText: ‘Previous‘,
    nextId: ‘nextBtn‘,
    nextText: ‘Next‘
    //……
  };
  //step 插件的扩展方法名称
  $.fn.easySlider = function (options) {
    //step-b 合并用户自定义属性，默认属性
    var options = $.extend(defaults, options);
    //step 支持JQuery选择器
    this.each(function () {
    });
  }
})(jQuery);

5. Support JQuery link call:

In order to achieve the effect of link calling, each element of the loop must be returned

//step 定义JQuery的作用域
(function ($) {
  //step-a 插件的默认值属性
  var defaults = {
    prevId: ‘prevBtn‘,
    prevText: ‘Previous‘,
    nextId: ‘nextBtn‘,
    nextText: ‘Next‘
    //……
  };
  //step 插件的扩展方法名称
  $.fn.easySlider = function (options) {
    //step-b 合并用户自定义属性，默认属性
    var options = $.extend(defaults, options);
    //step 支持JQuery选择器
    //step 支持链式调用
    return this.each(function () {
    });
  }
})(jQuery);

6. Methods in the plug-in:

The methods defined in the plug-in cannot be directly called by the outside world. The methods I defined in the plug-in do not pollute the external environment.

//step01 定义JQuery的作用域
(function ($) {
  //step03-a 插件的默认值属性
  var defaults = {
    prevId: ‘prevBtn‘,
    prevText: ‘Previous‘,
    nextId: ‘nextBtn‘,
    nextText: ‘Next‘
    //……
  };
  //step06-a 在插件里定义方法
  var showLink = function (obj) {
    $(obj).append(function () { return "(" + $(obj).attr("href") + ")" });
  }
  //step02 插件的扩展方法名称
  $.fn.easySlider = function (options) {
    //step03-b 合并用户自定义属性，默认属性
    var options = $.extend(defaults, options);
    //step4 支持JQuery选择器
    //step5 支持链式调用
    return this.each(function () {
      //step06-b 在插件里定义方法
      showLink(this);
    });
  }
})(jQuery);

The above content introduces you to the method of defining plug-ins with jQuery. I hope you like it.