深入学习jquery源码之attr()与removeAttr()

深入学习jquery源码之attr()与removeAttr()

attr(name|properties|key,value|fn)

概述

设置或返回被选元素的属性值。

参数

name String

属性名称

properties Map

作为属性的“名/值对”对象

key,value String,Object

属性名称，属性值

key,function(index, attr) String,Function

1:属性名称。

2:返回属性值的函数,第一个参数为当前元素的索引值，第二个参数为原先的属性值。

返回文档中所有图像的src属性值。

$("img").attr("src");

为所有图像设置src和alt属性。

$("img").attr({ src: "test.jpg", alt: "Test Image" });

为所有图像设置src属性。

$("img").attr("src","test.jpg");

把src属性的值设置为title属性的值。

$("img").attr("title", function() { return this.src });

 

removeAttr(name)

概述

从每一个匹配的元素中删除一个属性

1.6以下版本在IE6使用JQuery的removeAttr方法删除disabled是无效的。解决的方法就是使用$("XX").prop("disabled",false); 1.7版本在IE6下已支持删除disabled。

参数

name String

要删除的属性名

将文档中图像的src属性删除

$("img").removeAttr("src");

[  ]

 

jquery源码

        // Multifunctional method to get and set values of a collection
    // The value/s can optionally be executed if it's a function
    var access = jQuery.access = function (elems, fn, key, value, chainable, emptyGet, raw) {
        var i = 0,
            length = elems.length,
            bulk = key == null;

        // Sets many values
        if (jQuery.type(key) === "object") {
            chainable = true;
            for (i in key) {
                jQuery.access(elems, fn, i, key[i], true, emptyGet, raw);
            }

            // Sets one value
        } else if (value !== undefined) {
            chainable = true;

            if (!jQuery.isFunction(value)) {
                raw = true;
            }

            if (bulk) {
                // Bulk operations run against the entire set
                if (raw) {
                    fn.call(elems, value);
                    fn = null;

                    // ...except when executing function values
                } else {
                    bulk = fn;
                    fn = function (elem, key, value) {
                        return bulk.call(jQuery(elem), value);
                    };
                }
            }

            if (fn) {
                for (; i < length; i++) {
                    fn(elems[i], key, raw ? value : value.call(elems[i], i, fn(elems[i], key)));
                }
            }
        }

        return chainable ?
            elems :

            // Gets
            bulk ?
            fn.call(elems) :
            length ? fn(elems[0], key) : emptyGet;
    };
	
	    var nodeHook, boolHook,
        attrHandle = jQuery.expr.attrHandle,
        ruseDefault = /^(?:checked|selected)$/i,
        getSetAttribute = support.getSetAttribute,
        getSetInput = support.input;
	
	jQuery.fn.extend({
        attr: function (name, value) {
            return access(this, jQuery.attr, name, value, arguments.length > 1);
        },

        removeAttr: function (name) {
            return this.each(function () {
                jQuery.removeAttr(this, name);
            });
        }
    });
	
	
    jQuery.extend({
        attr: function (elem, name, value) {
            var hooks, ret,
                nType = elem.nodeType;

            // don't get/set attributes on text, comment and attribute nodes
            if (!elem || nType === 3 || nType === 8 || nType === 2) {
                return;
            }

            // Fallback to prop when attributes are not supported
            if (typeof elem.getAttribute === strundefined) {
                return jQuery.prop(elem, name, value);
            }

            // All attributes are lowercase
            // Grab necessary hook if one is defined
            if (nType !== 1 || !jQuery.isXMLDoc(elem)) {
                name = name.toLowerCase();
                hooks = jQuery.attrHooks[name] ||
                    (jQuery.expr.match.bool.test(name) ? boolHook : nodeHook);
            }

            if (value !== undefined) {

                if (value === null) {
                    jQuery.removeAttr(elem, name);

                } else if (hooks && "set" in hooks && (ret = hooks.set(elem, value, name)) !== undefined) {
                    return ret;

                } else {
                    elem.setAttribute(name, value + "");
                    return value;
                }

            } else if (hooks && "get" in hooks && (ret = hooks.get(elem, name)) !== null) {
                return ret;

            } else {
                ret = jQuery.find.attr(elem, name);

                // Non-existent attributes return null, we normalize to undefined
                return ret == null ?
                    undefined :
                    ret;
            }
        },

        removeAttr: function (elem, value) {
            var name, propName,
                i = 0,
                attrNames = value && value.match(rnotwhite);

            if (attrNames && elem.nodeType === 1) {
                while ((name = attrNames[i++])) {
                    propName = jQuery.propFix[name] || name;

                    // Boolean attributes get special treatment (#10870)
                    if (jQuery.expr.match.bool.test(name)) {
                        // Set corresponding property to false
                        if (getSetInput && getSetAttribute || !ruseDefault.test(name)) {
                            elem[propName] = false;
                            // Support: IE