JQuery Object

    init = jQuery.fn.init = function( selector, context ) {
    var match, elem;

    // HANDLE: $(""), $(null), $(undefined), $(false)
    if ( !selector ) {
        return this;
    }

    // Handle HTML strings
    if ( typeof selector === "string" ) {
        if ( selector[0] === "<" && selector[ selector.length - 1 ] === ">" && selector.length >= 3 ) {
            // Assume that strings that start and end with <> are HTML and skip the regex check
            match = [ null, selector, null ]; //如果是 html 标签， 直接赋值 match

        } else {
            match = rquickExpr.exec( selector ); //其他情况走正则处理，正则只找有没有<tag>或者 #id
        }

        // Match html or make sure no context is specified for #id
        //match代表是否匹配上了，匹配上<tag>放match[1]里 匹配上#id 放match[2]里
        if ( match && (match[1] || !context) ) {

            // HANDLE: $(html) -> $(array)
            //匹配上 tag 标签了
            if ( match[1] ) {
                context = context instanceof jQuery ? context[0] : context;

                // scripts is true for back-compat
                // Intentionally let the error be thrown if parseHTML is not present
                jQuery.merge( this, jQuery.parseHTML(
                    match[1],
                    context && context.nodeType ? context.ownerDocument || context : document,
                    true
                ) );

                // HANDLE: $(html, props)
                if ( rsingleTag.test( match[1] ) && jQuery.isPlainObject( context ) ) {
                    for ( match in context ) {
                        // Properties of context are called as methods if possible
                        if ( jQuery.isFunction( this[ match ] ) ) {
                            this[ match ]( context[ match ] );

                        // ...and otherwise set as attributes
                        } else {
                            this.attr( match, context[ match ] );
                        }
                    }
                }

                return this;

            // HANDLE: $(#id)
            //匹配上 id 了
            } else {
                elem = document.getElementById( match[2] );

                // Check parentNode to catch when Blackberry 4.6 returns
                // nodes that are no longer in the document #6963
                if ( elem && elem.parentNode ) {
                    // Inject the element directly into the jQuery object
                    this.length = 1;
                    this[0] = elem;
                }

                this.context = document;
                this.selector = selector;
                return this;
            }

        // HANDLE: $(expr, $(...))
        //如果没匹配上 分别看看其他的情况 例如非 id 的其他选择器.css tag
        } else if ( !context || context.jquery ) {
            return ( context || rootjQuery ).find( selector );

        // HANDLE: $(expr, context)
        // (which is just equivalent to: $(context).find(expr)
        } else {
            return this.constructor( context ).find( selector );
        }

    // HANDLE: $(DOMElement)
    //或者就是个 dom 元素
    } else if ( selector.nodeType ) {
        this.context = this[0] = selector;
        this.length = 1;
        return this;

    // HANDLE: $(function)
    // Shortcut for document ready
    //Jquery Ready 传参是函数啊
    } else if ( jQuery.isFunction( selector ) ) {
        return typeof rootjQuery.ready !== "undefined" ?
            rootjQuery.ready( selector ) :
            // Execute immediately if ready is not present
            selector( jQuery );
    }
    //这两句是对后面 makeArray传参的预处理，不明觉厉
    if ( selector.selector !== undefined ) {
        this.selector = selector.selector;
        this.context = selector.context;
    }
    其他一些情况 比如就传了个对象类似{a:1,b:2}
    return jQuery.makeArray( selector, this );//其实还是把传进去的对象 挂在了 JQuery 对象的0位置上
};

匹配上 HTML Tag String 之后详细的处理没看，下次再说吧。