jQuery 常用代码集锦

1. 选择或者不选页面上全部复选框

var tog = false; // or true if they are checked on load
$(‘a‘).click(function() {
    $("input[type=checkbox]").attr("checked",!tog);
    tog = !tog;
});

2. 取得鼠标的X和Y坐标

$(document).mousemove(function(e){
$(document).ready(function() {
$().mousemove(function(e){
$(‘#XY‘).html("Gbin1 X Axis : " + e.pageX + " | Gbin1 Y Axis " + e.pageY);
});
});

3. 判断一个图片是否加载完全

$(‘#theGBin1Image‘).attr(‘src‘, ‘image.jpg‘).load(function() {
alert(‘This Image Has Been Loaded‘);
});

4. 判断cookie是否激活或者关闭

var dt = new Date();
dt.setSeconds(dt.getSeconds() + 60);
document.cookie = "cookietest=1; expires=" + dt.toGMTString();
var cookiesEnabled = document.cookie.indexOf("cookietest=") != -1;
if(!cookiesEnabled)
{
  //cookies have not been enabled
}

5. 强制过期cookie

var date = new Date();
date.setTime(date.getTime() + (x * 60 * 1000));
$.cookie(‘example‘, ‘foo‘, { expires: date });

6. 在表单中禁用“回车键”，表单的操作中需要防止用户意外的提交表单

$("#form").keypress(function(e) {
  if (e.which == 13) {
    return false;
  }
});

7. 清除所有的表单数据

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;
  });
};

8.禁止多次递交表单

$(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;
    }
  });
});

9. 自动将数据导入selectbox中

$(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 += ‘<option value="‘ + j[i].optionValue + ‘">‘ + j[i].optionDisplay + ‘</option>‘;
      }
      $("select#ctlPerson").html(options);
    })
  })
})

10. 创建一个嵌套的过滤器

.filter(":not(:has(.selected))") //去掉所有不包含class为.selected的元素

11. 使用has()来判断一个元素是否包含特定的class或者元素

//jQuery 1.4.* includes support for the has method. This method will find
//if a an element contains a certain other element class or whatever it is
//you are looking for and do anything you want to them.
$("input").has(".email").addClass("email_icon");

12. 使用jQuery切换样式

//Look for the media-type you wish to switch then set the href to your new style sheet
$(‘link[media=‘screen‘]‘).attr(‘href‘, ‘Alternative.css‘);  

13. 如何正确使用ToggleClass

//Toggle class allows you to add or remove a class
//from an element depending on the presence of that
//class. Where some developers would use:
a.hasClass(‘blueButton‘) ? a.removeClass(‘blueButton‘) : a.addClass(‘blueButton‘);
//toggleClass allows you to easily do this using
a.toggleClass(‘blueButton‘); 

14. 使用jQuery来替换一个元素

$(‘#thatdiv‘).replaceWith(‘fnuh‘);

15.绑定一个函数到一个事件

$(‘#foo‘).bind(‘click‘, function() {
  alert(‘User clicked on "foo."‘);
}); 

16. 使用jQuery预加载图片

jQuery.preloadImages = function() { for(var i = 0; i‘).attr(‘src‘, arguments[i]); } };
// Usage $.preloadImages(‘image1.gif‘, ‘/path/to/image2.png‘, ‘some/image3.jpg‘); 

17. 设置任何匹配一个选择器的事件处理程序

$(‘button.someClass‘).live(‘click‘, someFunction);
  //Note that in jQuery 1.4.2, the delegate and undelegate options have been
  //introduced to replace live as they offer better support for context
    //For example, in terms of a table where before you would use..
  // .live()
  $("table").each(function(){
    $("td", this).live("hover", function(){
    $(this).toggleClass("hover");
    });
  });
  //Now use..
  $("table").delegate("td", "hover", function(){
  $(this).toggleClass("hover");
});

18. 自动的滚动到页面特定区域

jQuery.fn.autoscroll = function(selector) {
  $(‘html,body‘).animate(
    {scrollTop: $(selector).offset().top},
    500
  );
}
//Then to scroll to the class/area you wish to get to like this:
$(‘.area_name‘).autoscroll();

19.检测各种浏览器

Detect Safari (if( $.browser.safari)),
Detect IE6 and over (if ($.browser.msie && $.browser.version > 6 )),
Detect IE6 and below (if ($.browser.msie && $.browser.version <= 6 )),
Detect FireFox 2 and above (if ($.browser.mozilla && $.browser.version >= ‘1.8‘ )

20.限制textarea的字符数量

jQuery.fn.maxLength = function(max){
  this.each(function(){
    var type = this.tagName.toLowerCase();
    var inputType = this.type? this.type.toLowerCase() : null;
    if(type == "input" && inputType == "text" || inputType == "password"){
      //Apply the standard maxLength
      this.maxLength = max;
    }
    else if(type == "textarea"){
      this.onkeypress = function(e){
        var ob = e || event;
        var keyCode = ob.keyCode;
        var hasSelection = document.selection? document.selection.createRange().text.length > 0 : this.selectionStart != this.selectionEnd;
        return !(this.value.length >= max && (keyCode > 50 || keyCode == 32 || keyCode == 0 || keyCode == 13) && !ob.ctrlKey && !ob.altKey && !hasSelection);
      };
      this.onkeyup = function(){
        if(this.value.length > max){
          this.value = this.value.substring(0,max);
        }
      };
    }
  });
};
//Usage:
$(‘#gbin1textarea‘).maxLength(500);

21.使用jQuery克隆元素

var cloned = $(‘#gbin1div‘).clone();

22. 元素屏幕居中

jQuery.fn.center = function () {
  this.css(‘position‘,‘absolute‘);
  this.css(‘top‘, ( $(window).height() - this.height() ) / +$(window).scrollTop() + ‘px‘);
  this.css(‘left‘, ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + ‘px‘);return this;
}
//Use the above function as: $(‘#gbin1div‘).center();

23 .简单的tab标签切换

jQuery(‘#meeting_tabs ul li‘).click(function(){
        jQuery(this).addClass(‘tabulous_active‘).siblings().removeClass(‘tabulous_active‘);
        jQuery(‘#tabs_container>.pane:eq(‘+jQuery(this).index()+‘)‘).show().siblings().hide();
 })

<div id="meeting_tabs">
                <ul>
                     <li class="tabulous_active"><a href="#" title="">进行中</a></li>
                      <li><a href="#" title="">未开始</a></li>
                      <li><a href="#" title="">已结束</a></li>
                       <li><a href="#" title="">全部</a></li>
                 </ul>
   <div id="tabs_container">
            <div  class="pane"     >1</div>
            <div  class="pane"     >2</div>
            <div  class="pane"     >3</div>
           <div  class="pane"     >4</div>
  </div>
</div>