直接拿来用的15个jQuery代码片段

发表过的一篇《10个超级有用的PHP代码片段果断收藏》吗？本文笔者将继续为你奉上15个超级有用的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。

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

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; });  

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);
}); 

本文收集的这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。