7个替开发者准备的有用的jQuery技巧

7个为开发者准备的有用的jQuery技巧
一、在新窗口打开链接
用下面的代码，你点击链接即可在新窗口打开：

$(document).ready(function() {
    //select all anchor tags that have http in the href
    //and apply the target=_blank
    $("a[href^='http']").attr('target','_blank');
});
二、设置等高的列
应用下面的代码，可以使得你的WEB应用每一列高度都想等：

<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 = col
    col = $(col);
    //Loop all the col
    col.each(function() {
        //Store the highest value
        if ($(this).height() > maxHeight) {
            maxHeight = $(this).height();
        }
    });
    //Set the height
    col.height(maxHeight);
}
</script>
三、jQuery预加载图像
这个小技巧可以提升页面加载图片的速度：

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…');
});
四、禁用鼠标右键
$(document).ready(function() {
    //catch the right-click context menu
    $(document).bind("contextmenu", function(e) {
        //warning prompt - optional
        alert("No right-clicking!");

        //delete the default context menu
        return false;
    });
});
五、设定计时器
$(document).ready(function() {
    window.setTimeout(function() {
        // some code
    }, 500);
});
六、计算子元素的个数
<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>
七、把元素定位到页面中间
<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>