【转】jQuery代码片段备用

在CSDN看到的，记下备用。原文：http://www.csdn.net/article/2013-07-16/2816238-15-jquery-code-snippets-for-developers

jQuery里提供了许多创建交互式网站的方法，在开发Web项目时，开发人员应该好好利用jQuery代码，它们不仅能给网站带来各种动画、特效，还会提高网站的用户体验。

本文收集了15段非常实用的jQuery代码片段，你可以直接复制黏贴到代码里，但请开发者注意了，要理解代码再使用哦。下面就让我们一起来享受jQuery代码的魅力之处吧。

1.预加载图片

(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");

源码

2. 让页面中的每个元素都适合在移动设备上展示

var scr = document.createElement('script');
scr.setAttribute('src', 'https://ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js');
document.body.appendChild(scr);
scr.onload = function(){
$('div').attr('class', '').attr('id', '').css({
'margin' : 0,
'padding' : 0,
'width': '100%',
'clear':'both'
});
};

源码

3.图像等比例缩放

$(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
});

源码

4.返回页面顶部

 // Back To Top
 $(document).ready(function(){
 $('.top').click(function() {
 $(document).scrollTo(0,500);
 });
 });
 //Create a link defined with the class .top
 <a href="#" class="top">Back To Top</a>

源码

5.使用jQuery打造手风琴式的折叠效果

 var accordion = {
 init: function(){
 var $container = $('#accordion');
 $container.find('li:not(:first) .details').hide();
 $container.find('li:first').addClass('active');
 $container.on('click','li a',function(e){
 e.preventDefault();
 var $this = $(this).parents('li');
 if($this.hasClass('active')){
 if($('.details').is(':visible')) {
 $this.find('.details').slideUp();
 } else {
 $this.find('.details').slideDown();
 }
 } else {
 $container.find('li.active .details').slideUp();
 $container.find('li').removeClass('active');
 $this.addClass('active');
 $this.find('.details').slideDown();
 }
 });
 }
 };

6.通过预加载图片廊中的上一幅下一幅图片来模仿Facebook的图片展示方式

 var nextimage = "/images/some-image.jpg";
 $(document).ready(function(){
 window.setTimeout(function(){
 var img = $("").attr("src", nextimage).load(function(){
 //all done
 });
 }, 100);
 });

源码

7.使用jQuery和Ajax自动填充选择框

 $(function(){
 $("select#ctlJob").change(function(){
 $.getJSON("/select.php",{id: $(this).val(), ajax: 'true'}, function(j){
 var options = '';
 for (var i = 0; i < j.length; i++) {
 options += '
 ' + j[i].optionDisplay + '
 ';
 }
 $("select#ctlPerson").html(options);
 })
 })
 })

源码

8.自动替换丢失的图片

 // Safe Snippet
 $("img").error(function () {
 $(this).unbind("error").attr("src", "missing_image.gif");
 });
 // Persistent Snipper
 $("img").error(function () {
 $(this).attr("src", "missing_image.gif");
 });

源码

9.在鼠标悬停时显示淡入/淡出特效

 $(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
 });
 });

源码

10.清空表单数据

 function clearForm(form) {
 // iterate over all of the inputs for the form
 // element that was passed in
 $(':input', form).each(function() {
 var type = this.type;
 var tag = this.tagName.toLowerCase(); // normalize case
 // it's ok to reset the value attr of text inputs,
 // password inputs, and textareas
 if (type == 'text' || type == 'password' || tag == 'textarea')
 this.value = "";
 // checkboxes and radios need to have their checked state cleared
 // but should *not* have their 'value' changed
 else if (type == 'checkbox' || type == 'radio')
 this.checked = false;
 // select elements need to have their 'selectedIndex' property set to -1
 // (this works for both single and multiple select elements)
 else if (tag == 'select')
 this.selectedIndex = -1;
 });
 };

源码

11.预防对表单进行多次提交

 $(document).ready(function() {
 $('form').submit(function() {
 if(typeof jQuery.data(this, "disabledOnSubmit") == 'undefined') {
 jQuery.data(this, "disabledOnSubmit", { submited: true });
 $('input[type=submit], input[type=button]', this).each(function() {
 $(this).attr("disabled", "disabled");
 });
 return true;
 }
 else
 {
 return false;
 }
 });
 });

源码

12.动态添加表单元素

//change event on password1 field to prompt new input
$('#password1').change(function() {
//dynamically create new input and insert after password1
$("#password1").append("");
});

源码

13.让整个Div可点击

blah blah blah. link
The following lines of jQuery will make the entire div clickable: $(".myBox").click(function(){ window.location=$(this).find("a").attr("href"); return false; });

源码

14.平衡高度或Div元素

 var maxHeight = 0;
 $("div").each(function(){
 if ($(this).height() > maxHeight) { maxHeight = $(this).height(); }
 });
 $("div").height(maxHeight);

源码

15. 在窗口滚动时自动加载内容

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);
});