Vi. jQuery source code analysis: jQuery prototype attributes and Methods

        97      jQuery.fn = jQuery.prototype = {        98      constructor: jQuery,        99      init: function( selector, context, rootjQuery ) { },         210     selector: "",                213     jquery: "1.7.2",                216     length: 0,                219     size: function() {},        223     toArray: function() {},                229     get: function( num ) {},               241     pushStack: function( elems, name, selector ) {},               270     each: function( callback, args ) {},        274     ready: function( fn ) { },        284     eq: function( i ) {},        291     first: function() {},        295     last: function() { },        299     slice: function() {},        304     map: function( callback ) { },        310     end: function() { },               316     push: push,        317     sort: [].sort,        318     splice: [].splice        };

The above are some attributes and methods on the prototype of jQuery of this version.
Selector: used to record the selector of the init parameter. but not necessarily equal.
$ ("Div"). selector; // "div"
$ ("Div"). find (p). selecctor; // "div p ";
This property is generally used for debugging.
Jquery: jQuery version number.
Length: number of elements.
Size (): equivalent to length, the memory overhead of length is smaller.
The remaining members will be introduced in the following sections.