//找出你希望切换的媒体类型（media-type），然后把href设置成新的样式表。
$(‘link[media="screen"]‘).attr(‘href’, ’Alternative.css’);

if ($.browser.msie) {// Internet Explorer其实不那么好用
}

if ($(‘#keks’).html().trim()) {//什么都没有找到;
}

if ($(‘#someDiv’ ).length) {//你妹，终于找到了
}

// 方法一
if (! $('#keks').html()) {
//什么都没有找到
}// 方法二
if ($('#keks').is(":empty")) {
//什么都没有找到
}

$(‘#someElement’).find(‘option:selected’);

$(document).bind(‘contextmenu’, function (e) {return false ;
});

$(document).ready(function() {window.setTimeout(function() {// some code}, 500);
});        

<div class="equalHeight" style="border:1px solid"><p>First Line</p><p>Second Line</p><p>Third Line</p>
</div>
<div class="equalHeight" style="border:1px solid"><p>Column Two</p>
</div>
<script src="http://apps.bdimg.com/libs/jquery/1.11.1/jquery.min.js"></script>
<script>
$(document).ready(function() {equalHeight('.equalHeight');
});
//global variable, this will store the highest height value
var maxHeight = 0;
function equalHeight(col) {//Get all the element with class = colcol = $(col);//Loop all the colcol.each(function() {//Store the highest valueif ($(this).height() > maxHeight) {maxHeight = $(this).height();}});//Set the height
 　　col.height(maxHeight);
}
</script>

jQuery.preloadImagesInWebPage = function() {for (var ctr = 0; ctr & lt; arguments.length; ctr++) {jQuery("").attr("src", arguments[ctr]);}
}// 使用方法：
$.preloadImages("image1.gif", "image2.gif", "image3.gif");// 检查图片是否被加载
$('#imageObject').attr('src', 'image1.gif').load(function() {alert('The image has been loaded…');
});

<div id="foo" style="width:200px;height: 200px;background: #ccc;"></div>
<script src="http://apps.bdimg.com/libs/jquery/1.11.1/jquery.min.js"></script>
<script type="text/javascript">
jQuery.fn.center = function() {this.css("position", "absolute");this.css("top", ($(window).height() - this.height()) / 2 + $(window).scrollTop() + "px");this.css("left", ($(window).width() - this.width()) / 2 + $(window).scrollLeft() + "px");return this;
}
//Use the above function as:
$('#foo').center();
</script>

$(document).ready(function() {//catch the right-click context menu$(document).bind("contextmenu", function(e) {//warning prompt - optionalalert("No right-clicking!");//delete the default context menureturn false;});
});

<div id="foo"><div id="bar"></div><div id="baz"><div id="biz"></div><span><span></span></span></div>
</div>
<script src="http://apps.bdimg.com/libs/jquery/1.11.1/jquery.min.js"></script>
<script type="text/javascript">//jQuery code to count child elements $("#foo > div").size()
alert($("#foo > div").size())
</script>

$(document).ready(function() {$().mousemove(function(e){$('# MouseCoordinates ').html("X Axis Position = " + e.pageX + " and Y Axis Position = " + e.pageY);});

$().mousemove(function(e){//display the x and y axis values inside the P element$('p').html("X Axis : " + e.pageX + " | Y Axis " + e.pageY);
});

$(document).ready(function() {//when the id="top" link is clicked$('#top').click(function() {//scoll the page back to the top$(document).scrollTo(0,500);}
});

<h1 id="anchor">admin10000.com</h1>
<a class="topLink" href="#anchor">返回顶端</a>

$(document).ready(function () {$("a.topLink").click(function () {$("html, body").animate({scrollTop: $($(this).attr("href")).offset().top + "px"}, {duration: 500,easing: "swing"});return false;});});

<ul id='nav'><li>导航一</li><li>导航二</li><li>导航三</li>
</ul>
//注意：代码需要修饰完善
$('#nav').click(function(e) {// 要知道siblings的使用
$(e.target).addClass('tclass').siblings('.tclass').removeClass('tclass');;});

//在某些场景下，我们可能需要反序访问通过JQuery选择器获取到的页面元素对象，这个怎么实现呢？看下面代码：//要掌握JQuery对象的get方法 以及数组的reverse方法即可
var arr = $('#nav').find('li').get().reverse();
$.each(arr,function(index,ele){.... ...});

$("#searchbox").focus(function(){$(this).val('')}).blur(function(){var $this = $(this);// '请搜索...'为搜索框默认值($this.val() === '')? $this.val('请搜索...') : null;});

setInterval(function() {  //每隔5秒钟刷新页面内容//获取的内容将增加到 id为content的元素后$("#content").load(url);}, 5000);

var cache = {};
$.data(cache,'key','value'); //缓存数据
//获取数据
$.data(cache,'key');

//方法一： 为JQuery重新命名为 $jvar $j = jQuery.noConflict();
$j('#id')....
//方法二： 推荐使用的方式

(function($){$(document).ready(function(){//这儿，你可以正常的使用JQuery语法
  });
})(jQuery);

$('#content').css({'width': $(window).width(),'height': $(window).height(),
});
// make sure div stays full width/height on resize
$(window).resize(function(){var $w = $(window);$('#content').css({'width': $w.width(),'height': $w.height(),});
});

<input type="password" name="pass" id="pass" />
<span id="passstrength"></span>
//下面的正则表达式建议各位收藏哦，项目上有可能会用得着
$('#pass').keyup(function(e) {//密码为八位及以上并且字母数字特殊字符三项都包括var strongRegex = new RegExp("^(?=.{8,})(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*\\W).*$", "g");//密码为七位及以上并且字母、数字、特殊字符三项中有两项，强度是中等 var mediumRegex = new RegExp("^(?=.{7,})(((?=.*[A-Z])(?=.*[a-z]))|((?=.*[A-Z])(?=.*[0-9]))|((?=.*[a-z])(?=.*[0-9]))).*$", "g");var enoughRegex = new RegExp("(?=.{6,}).*", "g");if (false == enoughRegex.test($(this).val())) {$('#passstrength').html('More Characters');} else if (strongRegex.test($(this).val())) {$('#passstrength').className = 'ok';$('#passstrength').html('Strong!');} else if (mediumRegex.test($(this).val())) {$('#passstrength').className = 'alert';$('#passstrength').html('Medium!');} else {$('#passstrength').className = 'error';$('#passstrength').html('Weak!');}return true;
});

$(window).bind("load", function() {// IMAGE RESIZE$('#product_cat_list img').each(function() {var maxWidth = 120;var maxHeight = 120;var ratio = 0;var width = $(this).width();var height = $(this).height();if(width > maxWidth){ratio = maxWidth / width;$(this).css("width", maxWidth);$(this).css("height", height * ratio);height = height * ratio;}var width = $(this).width();var height = $(this).height();if(height > maxHeight){ratio = maxHeight / height;$(this).css("height", maxHeight);$(this).css("width", width * ratio);width = width * ratio;}});//$("#contentpage img").show();// IMAGE RESIZE
});

var loading = false;
$(window).scroll(function(){if((($(window).scrollTop()+$(window).height())+250)>=$(document).height()){if(loading == false){loading = true;$('#loadingbar').css("display","block");$.get("load.php?start="+$('#loaded_max').val(), function(loaded){$('body').append(loaded);$('#loaded_max').val(parseInt($('#loaded_max').val())+50);$('#loadingbar').css("display","none");loading = false;});}}
});
$(document).ready(function() {$('#loaded_max').val(50);
});

$.urlParam = function(name){var results = new RegExp('[\\?&]' + name + '=([^&#]*)').exec(window.location.href);if (!results) { return 0; }return results[1] || 0;
}

$("#form").keypress(function(e) {if (e.which == 13) {return false;}
});