【转】7个有用的jQuery代码片段

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() {
  $("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>

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