/*

17:10 2019/8/6

@author zhangxingshuo

jQuery:"write less, do more"       homepage: https://jquery.com/

jquery-1.12.4.js-|

jquery-2.2.4.js--|- from         jQuery CDN: https://code.jquery.com/

jquery-3.4.1.js--|

┌ ┬ ┐

├ ┼ ┤

└ ┴ ┘

search for "length" and "size()" in three files, the results are as follow:

        1.12.4  2.2.4   3.4.1

length  true    true    true

size()  true    true    false

for more details:

in jquery1.12.4

101-102行:

*/

// The default length of a jQuery object is 0

length: 0,

    /*

    10949-10952行:

    */

// The number of elements contained in the matched element set

    jQuery.fn.size = function() {

        return this.length;

    };

/*

jquery2.2.4

101-102行:

*/

// The default length of a jQuery object is 0

length: 0,

    /*

    9755-9757行:

    */

    size: function() {

    return this.length;

}

/*

jquery3.4.1中

166-167行:

*/

// The default length of a jQuery object is 0

length: 0,