10个可以直接拿来用的JQuery代码片段

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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10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;

  });

};