文章源自:http://www.csdn.net/article/2013-07-16/2816238-15-jQuery-Code-Snippets-for-Developers

可以直接拿来用的15个jQuery代码片段

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");

 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'
    });
};

 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
});

 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>

 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);
});

 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);
})
})
})

 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");
});

 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
    });
});

 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;
  });
};

 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;
    }
  });
});

 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("");
});

 13.让整个Div可点击

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

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);

 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);
});