深入学习jquery源码之empty()与返回值remove()

深入学习jquery源码之empty()与返回值remove()

empty()

概述

删除匹配的元素集合中所有的子节点。

把所有段落的子元素（包括文本节点）删除

<p>Hello, <span>Person</span> <a href="#">and person</a></p>

$("p").empty();

<p></p>

 

remove([expr])

概述

从DOM中删除所有匹配的元素。

这个方法不会把匹配的元素从jQuery对象中删除，因而可以在将来再使用这些匹配的元素。但除了这个元素本身得以保留之外，其他的比如绑定的事件，附加的数据等都会被移除。

参数

expr String

用于筛选元素的jQuery表达式

从DOM中把所有段落删除

<p>Hello</p> how are <p>you?</p>

$("p").remove();

how are

从DOM中把带有hello类的段落删除

<p class="hello">Hello</p> how are <p>you?</p>

$("p").remove(".hello");

how are <p>you?</p>

 

jquery源码

/**
     * Determines whether an object can have data
     */
    jQuery.acceptData = function (elem) {
        var noData = jQuery.noData[(elem.nodeName + " ").toLowerCase()],
            nodeType = +elem.nodeType || 1;

        // Do not set data on non-element DOM nodes because it will not be cleared (#8335).
        return nodeType !== 1 && nodeType !== 9 ?
            false :

            // Nodes accept data unless otherwise specified; rejection can be conditional
            !noData || noData !== true && elem.getAttribute("classid") === noData;
    };
    
        jQuery.extend({
        // Unique for each copy of jQuery on the page
        expando: "jQuery" + (version + Math.random()).replace(/\D/g, ""),
        now: function () {
            return +(new Date());
        },

        // jQuery.support is not used in Core but other projects attach their
        // properties to it so it needs to exist.
        support: support
       });
       
    
    jQuery.extend({
        cleanData: function (elems, /* internal */ acceptData) {
            var elem, type, id, data,
                i = 0,
                internalKey = jQuery.expando,
                cache = jQuery.cache,
                deleteExpando = support.deleteExpando,
                special = jQuery.event.special;

            for (; (elem = elems[i]) != null; i++) {
                if (acceptData || jQuery.acceptData(elem)) {

                    id = elem[internalKey];
                    data = id && cache[id];

                    if (data) {
                        if (data.events) {
                            for (type in data.events) {
                                if (special[type]) {
                                    jQuery.event.remove(elem, type);

                                    // This is a shortcut to avoid jQuery.event.remove's overhead
                                } else {
                                    jQuery.removeEvent(elem, type, data.handle);
                                }
                            }
                        }

                        // Remove cache only if it was not already removed by jQuery.event.remove
                        if (cache[id]) {

                            delete cache[id];

                            // IE does not allow us to delete expando properties from nodes,
                            // nor does it have a removeAttribute function on Document nodes;
                            // we must handle all of these cases
                            if (deleteExpando) {
                                delete elem[internalKey];

                            } else if (typeof elem.removeAttribute !== strundefined) {
                                elem.removeAttribute(internalKey);

                            } else {
                                elem[internalKey] = null;
                            }

                            deletedIds.push(id);
                        }
                    }
                }
            }
        }
    });
    
        function getAll(context, tag) {
        var elems, elem,
            i = 0,
            found = typeof context.getElementsByTagName !== strundefined ? context.getElementsByTagName(tag || "*") :
                typeof context.querySelectorAll !== strundefined ? context.querySelectorAll(tag || "*") :
                undefined;

        if (!found) {
            for (found = [], elems = context.childNodes || context; (elem = elems[i]) != null; i++) {
                if (!tag || jQuery.nodeName(elem, tag)) {
                    found.push(elem);
                } else {
                    jQuery.merge(found, getAll(elem, tag));
                }
            }
        }

        return tag === undefined || tag && jQuery.nodeName(context, tag) ?
            jQuery.merge([context], found) :
            found;
    }

    jQuery.fn.extend({
        remove: function (selector, keepData /* Internal Use Only */) {
            var elem,
                elems = selector ? jQuery.filter(selector, this) : this,
                i = 0;

            for (; (elem = elems[i]) != null; i++) {

                if (!keepData && elem.nodeType === 1) {
                    jQuery.cleanData(getAll(elem));
                }

                if (elem.parentNode) {
                    if (keepData && jQuery.contains(elem.ownerDocument, elem)) {
                        setGlobalEval(getAll(elem, "script"));
                    }
                    elem.parentNode.removeChild(elem);
                }
            }

            return this;
        },
        empty: function () {
            var elem,
                i = 0;

            for (; (elem = this[i]) != null; i++) {
                // Remove element nodes and prevent memory leaks
                if (elem.nodeType === 1) {
                    jQuery.cleanData(getAll(elem, false));
                }

                // Remove any remaining nodes
                while (elem.firstChild) {
                    elem.removeChild(elem.firstChild);
                }

                // If this is a select, ensure that it displays empty (#12336)
                // Support: IE<9
                if (elem.options && jQuery.nodeName(elem, "select")) {
                    elem.options.length = 0;
                }
            }

            return this;
        }

    });