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10 个很棒的 jQuery 代码片段

jQuery 代码片段

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#1 冰力

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发表于 2011/11/23 09:54:52

jQuery gave a new life to JavaScript coding. Thanks to this great tool, it is now possible to build powerful and responsive web pages. In this article, I have compiled 10 jQuery snippets that will definitely help you in your daily client-side coding.

图片预加载(Preloading images)

Preloading images is useful: Instead of loading an image when the user request it, we preload them in the background so they are ready to be displayed. Doing so in jQuery is very simple, as shown below:
(function($) {
  var cache = [];
  // Arguments are image paths relative to the current page.
  $.preLoadImages = function() {
	var args_len = arguments.length;
	for (var i = args_len; i--;)/> {
	  var cacheImage = document.createElement('img');
	  cacheImage.src = arguments[i];
	  cache.push(cacheImage);
	}
  }

jQuery.preLoadImages("image1.gif", "/path/to/image2.png");

在新窗口打开链接(target=”blank” links)

The following snippet will open all links with the rel="external" attribute in a new tab/window. The code can be easily customized to only open links with a specific class.
$('a[@rel$='external']').click(function(){
	 this.target = "_blank";
});

/*
   Usage:
   <a href="http://www.catswhocode.com" rel="external">catswhocode.com</a>
*/

当支持 JavaScript 时为 body 增加 class(Add a class to the <body> tag if JavaScript is enabled)

This snippet is just a line of code, but it is one of the easiest way to detect if JavaScript is enabled on the client browser. If yes, a hasJS class will be added to the <body> tag.
$('body').addClass('hasJS');

平滑滚动页面到某个锚点(Smooth scrolling to an anchor)

jQuery is known for its ability to let developers easily create stunning visual effects. A simple, but nice effect is smooth sliding to an anchor. The following snippet will create a smooth sliding effect when a link with the topLink class is clicked.
$(document).ready(function() {
	$("a.topLink").click(function() {
		$("html, body").animate({
			scrollTop: $($(this).attr("href")).offset().top + "px"
		}, {
			duration: 500,
			easing: "swing"
		});
		return false;
	});
});

鼠标滑动时的渐入和渐出(Fade in/out on hover)

Another very cool effect – which is very popular among clients – is indeed the fade in/fade out on mouseover. The code below set opacity to 100% on hover, and to 60% on mouseout.
$(document).ready(function(){
	$(".thumbs img").fadeTo("slow", 0.6); // This sets the opacity of the thumbs to fade down to 60% when the page loads

	$(".thumbs img").hover(function(){
		$(this).fadeTo("slow", 1.0); // This should set the opacity to 100% on hover
	},function(){
		$(this).fadeTo("slow", 0.6); // This should set the opacity back to 60% on mouseout
	});
});

制作等高的列(Equal column height)

When building a column based website, you often want that all columns have the same height, as displayed in a good old table. This snippet calculate the height of the higher column and automatically adjust all other columns to this height.
var max_height = 0;
$("div.col").each(function(){
	if ($(this).height() > max_height) { max_height = $(this).height(); }
});
$("div.col").height(max_height);

在一些老的浏览器上启用 HTML5 的支持(Enable HTML5 markup on older browsers)

HTML5 is definitely the future of client-side web development. Unfortunely, some old browsers do not even recognize new tags such as header or section. This code will force old browsers to recognize the new tags introduced by HTML5.
(function(){if(!/*@cc_on!@*/0)return;var e = "abbr,article,aside,audio,bb,canvas,datagrid,datalist,details,dialog,eventsource,figure,footer,header,hgroup,mark,menu,meter,nav,output,progress,section,time,video".split(','),i=e.length;while(i--){document.createElement(e[i])}})()

A better solution is to link the .js file to the <head> part of your HTML page:
<!--[if lt IE 9]>
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->


测试浏览器是否支持某些 CSS3 属性(Test if the browser supports a specific CSS3 property)

Here is a simple jQuery function to check if the client browser supports a specific CSS3 property. In this example, border-radius is the property we want to check, but of course this can be modified easily.
Note that when passing the property, you have to omit the dash to prevent syntax error. So instead of border-radius, you have to pass “borderRadius” or “BorderRadius”.
var supports = (function() {
   var div = document.createElement('div'),
	  vendors = 'Khtml Ms O Moz Webkit'.split(' '),
	  len = vendors.length;

   return function(prop) {
	  if ( prop in div.style ) return true;

	  prop = prop.replace(/^[a-z]/, function(val) {
		 return val.toUpperCase();
	  });

	  while(len--) {
		 if ( vendors[len] + prop in div.style ) {
			// browser supports box-shadow. Do what you need.
			// Or use a bang (!) to test if the browser doesn't.
			return true;
		 }
	  }
	  return false;
   };
})();

if ( supports('textShadow') ) {
   document.documentElement.className += ' textShadow';

获取 URL 中传递的参数(Get url parameters)

Getting url parameters is pretty easy using jQuery. The following snippet will do the job!
$.urlParam = function(name){
	var results = new RegExp('[\\?&]' + name + '=([^&#]*)').exec(window.location.href);
	if (!results) { return 0; }
	return results[1] || 0;
}

禁用表单的回车键提交(Disable the “Enter” key in forms)

By default, a form can be submitted by pressing the “Enter” key. Thought, on some form, this keyboard shortcut can cause problems. Here is how you can prevent unwanted form submission by disabling the “Enter” key with jQuery.
$("#form").keypress(function(e) {
  if (e.which == 13) {
	return false;
  }
});