$(document).ready(function() {
  //select all anchor tags that have http in the href
  //and apply the target=_blank
  $("a[href^='http']").attr('target','_blank');
});

<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>

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…');
});

$(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;
  });
});

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

<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>

<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>