jquery常用方法

由于当前jQuery如此的如雷贯耳，相信不用介绍什么是jQuery了，公司代码中广泛应用了jQuery，但我在看一些小朋友的代码时发现一个问题，小朋友们使用的仅仅是jQuery的皮毛，只是使用id选择器与attr方法，还有几个动画，如果只是如此，相比于其带来的开销，其实还不如不使用，下面介绍几个jQuery常用的方法，来让jQuery的威力发挥出来，否则只用有限的几个方法，相对于运行速度问题，真不如不用jQuery。

jQuery如此之好用，和其在获取对象时使用与CSS选择器兼容的语法有很大关系，毕竟CSS选择器大家都很熟悉（关于CSS选择器可以看看十分钟搞定CSS选择器），但其强大在兼容了CSS3的选择器，甚至多出了很多。

选择器

有了CSS选择器基础后，看jQuery的选择器就很简单了，不再详细一一说明

筛选方法

.find(selector) 查找集合每个元素的子节点

Get the descendants(子节点) of each element in the current set of matched elements, filtered by a selector, jQuery object, or element.

$('li.item-ii').find('li').css('background-color', 'red');

.filter(selector) 过滤当前集合内元素

Reduce(减少) the set of matched elements to those that match the selector or pass the function's test.

$('li').filter(':even').css('background-color', 'red');

基本方法

.ready(handler) 文档加载完成后执行的方法，区别于window.onload

Specify a function to execute when the DOM is fully loaded.

$(document).ready(function() {
  // Handler for .ready() called.
});

.each(function(index,element)) 遍历集合内每个元素

Iterate over a jQuery object, executing a function for each matched element.

$("li" ).each(function( index ) {
  console.log( index + ": " + $(this).text() );
});

jQuery.extend( target [, object1 ] [, objectN ] ) 合并对象

Merge the contents of two or more objects together into the first object.

var object = $.extend({}, object1, object2);

获取元素

.eq(index) 按index获取jQuery对象集合中的某个特定jQuery对象

Reduce the set of matched elements to the one at the specified index.

.eq(-index) 按逆序index获取jQuery对象集合中的某个特定jQuery对象

• An integer indicating the position of the element, counting backwards from the last element in the set.

$( "li" ).eq( 2 ).css( "background-color", "red" );

.get(index) 获取jQuery集合对象中某个特定index的DOM对象（将jQuery对象自动转换为DOM对象）

Retrieve one of the DOM elements matched by the jQuery object.

console.log( $( "li" ).get( -1 ) );

.get() 将jQuery集合对象转换为DOM集合对象并返回

Retrieve the DOM elements matched by the jQuery object.

console.log( $( "li" ).get() );

.index() / .index(selector)/ .index(element) 从给定集合中查找特定元素index

Search for a given element from among the matched elements.

1. 没参数返回第一个元素index

2.如果参数是DOM对象或者jQuery对象，则返回参数在集合中的index

3.如果参数是选择器，返回第一个匹配元素index，没有找到返回-1

var listItem = $( "#bar" );
alert( "Index: " + $( "li" ).index( listItem ) );

.clone（[withDataAndEvents][,deepWithDataAndEvents]) 创建jQuery集合的一份deep copy（子元素也会被复制），默认不copy对象的shuju和绑定事件

Create a deep copy of the set of matched elements.

$( ".hello" ).clone().appendTo( ".goodbye" );

.parent([selector]) 获取jQuery对象符合selector的父元素

Get the parent of each element in the current set of matched elements, optionally filtered by a selector.

$( "li.item-a" ).parent('ul').css( "background-color", "red" );

.parents([selector]) 获取jQuery对象符合选择器的祖先元素

Get the ancestors of each element in the current set of matched elements, optionally filtered by a selector.

$( "span.selected" ) .parents( "div" ) .css( "border", "2px red solid" )

插入元素

.append(content[,content]) / .append(function(index,html)) 向对象尾部追加内容

Insert content, specified by the parameter, to the end of each element in the set of matched elements.

1. 可以一次添加多个内容，内容可以是DOM对象、HTML string、 jQuery对象

2. 如果参数是function，function可以返回DOM对象、HTML string、 jQuery对象，参数是集合中的元素位置与原来的html值

$( ".inner" ).append( "<p>Test</p>" );
$( "body" ).append( $newdiv1, [ newdiv2, existingdiv1 ] );
$( "p" ).append( "<strong>Hello</strong>" );
$( "p" ).append( $( "strong" ) );
$( "p" ).append( document.createTextNode( "Hello" ) );

.appendTo(target) 把对象插入到目标元素尾部，目标元素可以是selector, DOM对象, HTML string, 元素集合,jQuery对象;

Insert every element in the set of matched elements to the end of the target.

$( "h2" ).appendTo( $( ".container" ) );
$( "<p>Test</p>" ).appendTo( ".inner" );

.prepend(content[,content]) / .prepend(function(index,html)) 向对象头部追加内容，用法和append类似

Insert content, specified by the parameter, to the beginning of each element in the set of matched elements.

$( ".inner" ).prepend( "<p>Test</p>" );

.prependTo(target) 把对象插入到目标元素头部，用法和prepend类似

Insert every element in the set of matched elements to the beginning of the target.

$( "<p>Test</p>" ).prependTo( ".inner" );

.before([content][,content]) / .before(function) 在对象前面(不是头部，而是外面，和对象并列同级)插入内容，参数和append类似

Insert content, specified by the parameter, before each element in the set of matched elements.

$( ".inner" ).before( "<p>Test</p>" );
$( ".container" ).before( $( "h2" ) );
$( "p" ).first().before( newdiv1, [ newdiv2, existingdiv1 ] );
$( "p" ).before( "<b>Hello</b>" );
$( "p" ).before( document.createTextNode( "Hello" ) );

.insertBefore(target) 把对象插入到target之前（同样不是头部，是同级）

Insert every element in the set of matched elements before the target.

$( "h2" ).insertBefore( $( ".container" ) );

.after([content][,content]) / .after(function（index）) 和before相反，在对象后面(不是尾部，而是外面，和对象并列同级)插入内容，参数和append类似

Insert content, specified by the parameter, after each element in the set of matched elements.

$( ".inner" ).after( "<p>Test</p>" );
$( "p" ).after( document.createTextNode( "Hello" ) );

.insertAfter(target) 和insertBefore相反，把对象插入到target之后（同样不是尾部，是同级）

Insert every element in the set of matched elements after the target.

$( "<p>Test</p>" ).insertAfter( ".inner" );
$( "p" ).insertAfter( "#foo" );

包裹元素

.wrap(wrappingElement) / .wrap(function(index)) 为每个对象包裹一层HTML结构，可以是selector, element, HTML string, jQuery object

Wrap an HTML structure around each element in the set of matched elements.

<div class="container">
  <div class="inner">Hello</div>
  <div class="inner">Goodbye</div>
</div>

$( ".inner" ).wrap( "<div class='new'></div>" );

<div class="container">
  <div class="new">
    <div class="inner">Hello</div>
  </div>
  <div class="new">
    <div class="inner">Goodbye</div>
  </div>
</div>

.wrapAll(wrappingElement) 把所有匹配对象包裹在同一个HTML结构中

Wrap an HTML structure around all elements in the set of matched elements.

<div class="container">
  <div class="inner">Hello</div>
  <div class="inner">Goodbye</div>
</div>

$( ".inner" ).wrapAll( "<div class='new' />");

<div class="container">
  <div class="new">
    <div class="inner">Hello</div>
    <div class="inner">Goodbye</div>
  </div>
</div>

.wrapInner(wrappingElement) / .wrapInner(function(index)) 包裹匹配元素内容，这个不好说，一看例子就懂

Wrap an HTML structure around the content of each element in the set of matched elements.

<div class="container">
  <div class="inner">Hello</div>
  <div class="inner">Goodbye</div>
</div>

$( ".inner" ).wrapInner( "<div class='new'></div>");

<div class="container">
  <div class="inner">
    <div class="new">Hello</div>
  </div>
  <div class="inner">
    <div class="new">Goodbye</div>
  </div>
</div>

.unwap() 把DOM元素的parent移除

Remove the parents of the set of matched elements from the DOM, leaving the matched elements in their place.

pTags = $( "p" ).unwrap();

属性方法

.val() 获取元素的value值

Get the current value of the first element in the set of matched elements.

$( "input:checkbox:checked" ).val();

.val(value) /.val(function(index,value)) 为元素设置值，index和value同样是指在为集合中每个元素设置的时候该元素的index和原value值

Set the value of each element in the set of matched elements.

$( "input" ).val( ‘hello’ );
$( "input" ).on( "blur", function() {
  $( this ).val(function( i, val ) {
    return val.toUpperCase();
  });
});

.attr(attributeName) 获取元素特定属性的值

Get the value of an attribute for the first element in the set of matched elements.

var title = $( "em" ).attr( "title" );

.attr(attributeName,value) / .attr(attributesJson) / .attr( attributeName, function(index, attr) ) 为元素属性赋值

Set one or more attributes for the set of matched elements.

$( "#greatphoto" ).attr( "alt", "Beijing Brush Seller" );

$( "#greatphoto" ).attr({
  alt: "Beijing Brush Seller",
  title: "photo by Kelly Clark"
});

$( "#greatphoto" ).attr( "title", function( i, val ) {
  return val + " - photo by Kelly Clark";
});

.prop( propertyName ) 获取元素某特性值

Get the value of a property for the first element in the set of matched elements.

$( elem ).prop( "checked" )

.prop(propertyName,value) / .prop(propertiesJson) / .prop(propertyName,function(index,oldPropertyValue)) 为元素特性赋值

Set one or more properties for the set of matched elements.

$( "input" ).prop( "checked", true );

$( "input[type='checkbox']" ).prop( "checked", function( i, val ) {
  return !val;
});

$( "input[type='checkbox']" ).prop({
  disabled: true
});

关于attribute 和 property区别可以看看 jQuery的attr与prop

.data(key,value) / .value(json) 为HTML DOM元素添加数据，HTML5元素 已有data-*属性

Store arbitrary data associated with the matched elements.The .data() method allows us to attach data of any type to DOM elements in a way that is safe from circular references and therefore from memory leaks.

$( "body" ).data( "foo", 52 );
$( "body" ).data( "bar", { myType: "test", count: 40 } );
$( "body" ).data( { baz: [ 1, 2, 3 ] } );

.data(key) / .data() 获取获取data设置的数据或者HTML5 data-*属性中的数据

Return the value at the named data store for the first element in the jQuery collection, as set by data(name, value) or by an HTML5 data-* attribute.

alert( $( "body" ).data( "foo" ) );
alert( $( "body" ).data() );

alert( $( "body" ).data( "foo" ) ); // undefined
$( "body" ).data( "bar", "foobar" );
alert( $( "body" ).data( "bar" ) ); // foobar

CSS方法

.hasClass(calssName) 检查元素是否包含某个class，返回true/false

Determine whether any of the matched elements are assigned the given class.

$( "#mydiv" ).hasClass( "foo" )

.addClass(className) / .addClass(function(index,currentClass)) 为元素添加class，不是覆盖原class，是追加，也不会检查重复

Adds the specified class(es) to each of the set of matched elements.

$( "p" ).addClass( "myClass yourClass" );

$( "ul li" ).addClass(function( index ) {
  return "item-" + index;
});

removeClass([className]) / ,removeClass(function(index,class)) 移除元素单个/多个/所有class

Remove a single class, multiple classes, or all classes from each element in the set of matched elements.

$( "p" ).removeClass( "myClass yourClass" );

$( "li:last" ).removeClass(function() {
  return $( this ).prev().attr( "class" );
});

.toggleClass(className) /.toggleClass(className,switch) /  .toggleClass([switch]) / .toggleClass( function(index, class, switch) [, switch ] ) toggle是切换的意思，方法用于切换，switch是个bool类型值，这个看例子就明白

Add or remove one or more classes from each element in the set of matched elements, depending on either the class's presence or the value of the switch argument.

<div class="tumble">Some text.</div>

第一次执行

$( "div.tumble" ).toggleClass( "bounce" )

<div class="tumble bounce">Some text.</div>

第二次执行

$( "div.tumble" ).toggleClass( "bounce" )

<div class="tumble">Some text.</div>

$( "#foo" ).toggleClass( className, addOrRemove );

// 两种写法意思一样

if ( addOrRemove ) {
  $( "#foo" ).addClass( className );
} else {
  $( "#foo" ).removeClass( className );
}

$( "div.foo" ).toggleClass(function() {
  if ( $( this ).parent().is( ".bar" ) ) {
    return "happy";
  } else {
    return "sad";
  }
});

.css(propertyName) / .css(propertyNames) 获取元素style特定property的值

Get the value of style properties for the first element in the set of matched elements.

var color = $( this ).css( "background-color" );

 var styleProps = $( this ).css([
    "width", "height", "color", "background-color"
  ]);

.css(propertyName,value) / .css( propertyName, function(index, value) ) / .css( propertiesJson ) 设置元素style特定property的值

Set one or more CSS properties for the set of matched elements.

$( "div.example" ).css( "width", function( index ) {
  return index * 50;
});

$( this ).css( "width", "+=200" );


$( this ).css( "background-color", "yellow" );

   $( this ).css({
      "background-color": "yellow",
      "font-weight": "bolder"
    });

事件方法

.bind( eventType [, eventData ], handler(eventObject) ) 绑定事件处理程序，这个经常用，不多解释

Attach a handler to an event for the elements.

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

.delegate( selector, eventType, handler(eventObject) ) 这个看官方解释吧

Attach a handler to one or more events for all elements that match the selector, now or in the future, based on a specific set of root elements.

$( "table" ).on( "click", "td", function() {//这样把td的click事件处理程序绑在table上
  $( this ).toggleClass( "chosen" );
});

.on( events [, selector ] [, data ], handler(eventObject) ) 1.7后推荐使用，取代bind、live、delegate

Attach an event handler function for one or more events to the selected elements.

$( "#dataTable tbody" ).on( "click", "tr", function() {
  alert( $( this ).text() );
});

关于bind、live、delegate、on的区别可以看看 jQuery三种事件绑定方式.bind(),.live(),.delegate()

未知BUG ：使用$(document).on("click", "elementID",function(){})为动态元素绑定点击事件，如果是在模态框使用，导致事件的重复执行。

.trigger( eventType [, extraParameters ] ) JavaScript出发元素绑定事件

Execute all handlers and behaviors attached to the matched elements for the given event type.

$( "#foo" ).trigger( "click" );

.toggle( [duration ] [, complete ] ) / .toggle( options ) 隐藏或显示元素

Display or hide the matched elements.

$( ".target" ).toggle();

$( "#clickme" ).click(function() {
  $( "#book" ).toggle( "slow", function() {
    // Animation complete.
  });
});

动画/Ajax

这两部分内容比较多，不是简单的一个function就可以的，这里只是列举一下常用方法名，关于其使用可以看看 jQuery API animation ajax ，或者 jQuery的动画处理总结，ASP.NET 使用Ajax

动画

queue/dequeue/clearQueue

delay/stop

fadeIn/fadeOut/fadeTo/fadeToggle

slideUp/slideDown/slideToggle

show/hide

Ajax

$.ajax

$.load

$.get

最后

了解了上面这些内容，使用jQuery进行web开发的时候就可以体验到jQuery的威力了。本文不是jQuery学习指南，仅仅是个常用方法介绍，如果大家想学习jQuery，最好的教材还是jQuery API，本文中示例与英文解释全部来源于jQuery API。 另外文中介绍内容远远不是jQuery全部，但是首先掌握了这些可以对jQuery有一个比较全面的认识，然后再学习其他内容的时候就可以游刃有余了。