说说你对闭包的明白

Talk about your understanding of closures

运用闭包主要是为了设想私有的要领和变量。闭包的长处是可以防备全局变量的污染，瑕玷是闭包会常驻内存，会增大内存运用量，运用不当很轻易形成内存泄漏。

Using closures designed primarily to private methods and variables. Closure advantage of global variables are avoided contamination, the disadvantage is the closure will be permanent memory, the memory usage increases, improper use is likely to cause a memory leak.

闭包有三个特征:

Closures have three characteristics:

1.函数嵌套函数

2.函数内部可以援用外部的参数和变量

3.参数和变量不会被渣滓接纳机制接纳

1. Function
2. The internal function nested function can refer to external parameters and variables
3. The parameters and variables will not be garbage collection mechanism Recycling

请你谈谈Cookie的弊病

You talk about the shortcomings of Cookie

cookie虽然在耐久保存客户端数据供应了轻易，分管了服务器存储的累赘，但照样有许多局限性的。
第一：每一个特定的域名下最多天生20个cookie

1.IE6或更低版本最多20个cookie
2.IE7和以后的版本末了可以有50个cookie。
3.Firefox最多50个cookie
4.chrome和Safari没有做硬性限定

1.IE6 or earlier up to 20 cookie 
2.IE7 later version and last may have 50 cookie. 
3.Firefox up to 50 cookie 
4.chrome and Safari does not do hard limit. IE and Opera will clean up the least recently used cookie , Firefox will randomly to clean cookie .

IE和Opera 会清算近期起码运用的cookie，Firefox会随机清算cookie。

cookie的最大大约为4096字节，为了兼容性，平常不能超过4095字节。

IE 供应了一种存储可以耐久化用户数据，叫做userdata，从IE5.0就最先支撑。每一个数据最多128K，每一个域名下最多1M。这个耐久化数据放在缓存中，假如缓存没有清算，那末会一向存在。

IE can provide a way to store persistent user data, called UserData , from IE5.0 has supported. Each data up to 128K, under each domain up to 1M. The persistent data in the cache, if not cleaned the cache, it will always exist.

长处：极高的扩展性和可用性

Advantages: high scalability and availability

1.经由过程优越的编程，掌握保存在cookie中的session对象的大小。
2.经由过程加密和平安传输手艺（SSL），削减cookie被破解的可能性。
3.只在cookie中寄存不敏感数据，纵然被盗也不会有重大损失。
4.掌握cookie的性命期，使之不会永久有用。偷窃者极可能拿到一个逾期的cookie。

1. Good programming, control the size of the session cookie stored in the object. 
2. encryption and secure transmission technology (SSL), to reduce the possibility of cookie to crack. 
3. Only non-sensitive data is stored in a cookie, even if stolen will not have significant losses. 
4. Control cookie lifetime, so it will not always be effective. Theft are likely to get an expired cookie.

瑕玷：

Disadvantages:

1.`Cookie`数目和长度的限定。每一个domain最多只能有20条cookie，每一个cookie长度不能超过4KB，不然会被截掉。

2.平安性题目。假如cookie被人阻拦了，那人就可以获得一切的session信息。纵然加密也与事无补，由于阻拦者并不须要晓得cookie的意义，他只需原样转发cookie就可以到达目标了。

3.有些状况不可能保存在客户端。比方，为了防备反复提交表单，我们须要在服务器端保存一个计数器。假如我们把这个计数器保存在客户端，那末它起不到任何作用。

1.`Cookie` limit the number and length. Each domain can have a maximum of 20 cookie, each cookie length can not exceed 4KB, otherwise it will be truncated. 

2. The security issues. If the cookie is intercepted, that person can get all the session information. Even if encryption is also unhelpful, because Interceptor does not need to know the meaning of the cookie, cookie forwarding as long as he can achieve their goals. 

3. Some state can not be stored in the client. For example, in order to prevent duplicate submission form, we need to save a counter on the server side. If we put this counter is stored in the client, then it will not achieve any effect.

Browser local storage

浏览器当地存储

在较高版本的浏览器中，js供应了sessionStorage和globalStorage。在HTML5中供应了localStorage来庖代globalStorage。

In later versions of the browser, JS provides sessionStorage and globalStorage . In HTML5 provides in localStorage to replace globalStorage.

html5中的Web Storage包括了两种存储体式格局：sessionStorage和localStorage。

html5 The Web Storage includes two storage methods: sessionStorage and localStorage .

sessionStorage用于当地存储一个会话（session）中的数据，这些数据只要在同一个会话中的页面才接见而且当会话完毕后数据也随之烧毁。因而sessionStorage不是一种耐久化的当地存储，仅仅是会话级别的存储。

sessionStorage data stored locally for a session (session) in which the data only in the same session of the page to access data, and when the end of the session also will be destroyed. So sessionStorage not a persistent local storage, just session-level storage.

而localStorage用于耐久化的当地存储，除非主动删除数据，不然数据是永久不会逾期的。

And localStorage for persistent local storage, unless the initiative to remove the data, or the data is never out of date.

web storage和cookie的辨别

the difference between web storage and a cookie

Web Storage的观点和cookie类似，辨别是它是为了更大容量存储设想的。Cookie的大小是受限的，而且每次你要求一个新的页面的时刻Cookie都邑被发送过去，如许无形中浪费了带宽，别的cookie还须要指定作用域，不可以跨域挪用。

Web Storage concept and cookie similar, except that it is designed for higher-capacity storage. Cookie size is limited, and every time you request a new page when the Cookie will be sent in the past, so that virtually waste bandwidth, another cookie also need to specify the scope, not cross-domain calls.

除此之外，Web Storage具有setItem,getItem,removeItem,clear等要领，不像cookie须要前端开辟者本身封装setCookie，getCookie。

In addition, Web Storage has setItem, getItem, removeItem, clear methods, unlike the cookie front-end developers need their own package setCookie, getCookie.

然则cookie也是不可以或缺的：cookie的作用是与服务器举行交互，作为HTTP范例的一部份而存在 ，而Web Storage仅仅是为了在当地“存储”数据而生

But the cookie is not indispensable: cookie ‘s role is to interact with the server as HTTP part of the specification exists, and Web Storage simply to the local “store” raw data

浏览器的支撑除了IE７及以下不支撑外，其他规范浏览器都完整支撑(ie及FF需在web服务器里运转)，值得一提的是IE老是办好事，比方IE7、IE6中的userData实在就是javascript当地存储的处理方案。经由过程简朴的代码封装可以一致到一切的浏览器都支撑web storage。

Browser support in addition to IE7 and below are not supported, other standard browsers fully support (ie and FF need to run a web server in), it is worth mentioning that IE always good things, such as IE7, IE6 in the userData fact is javascript local storage solutions. By simple code package can be unified to all the browsers support Web storage.

localStorage和sessionStorage都具有雷同的操作要领，比方setItem、getItem和removeItem等

localStorage and sessionStorage have the same method of operation, for example setItem, getItem and removeItem etc.

cookie 和session 的辨别：

cookie and session distinction:

 1、cookie数据寄存在客户的浏览器上，session数据放在服务器上。
 2、cookie不是很平安，他人可以剖析寄存在当地的COOKIE并举行COOKIE诳骗
    考虑到平安应该运用session。
 3、session会在肯定时间内保存在服务器上。当接见增添，会比较占用你服务器的机能
     考虑到减轻服务器机能方面，应该运用COOKIE。
 4、单个cookie保存的数据不能超过4K，许多浏览器都限定一个站点最多保存20个cookie。
 5、所以个人发起：
    将上岸信息等主要信息寄存为SESSION
    其他信息假如须要保存，可以放在COOKIE中
    
 1, cookie data is stored on the customer's browser, session data on the server. 
 2, cookie is not very safe, others can be analyzed at a local store and COOKIE COOKIE cheat should be used taking into account the security session. 
 3, session will be within a certain time saved on the server. When accessing the increase, it would be more occupy the performance of your server consider to reduce server performance, you should use COOKIE. 
 4, the data stored in a single cookie can not exceed 4K, many browsers are limited to a maximum of one site to save 20 cookie. 
 5, so personal recommendations: the login information and other important information is stored as SESSION additional information, if necessary, it can be placed in COOKIE

CSS 相干题目

CSS-related issues

display:none和visibility:hidden的辨别？

display: none and visibility: hidden difference?

display:none  隐蔽对应的元素，在文档规划中不再给它分派空间，它各边的元素会合拢，
就当他历来不存在。

visibility:hidden  隐蔽对应的元素，然则在文档规划中仍保存本来的空间。

display: none to hide the corresponding elements in the document layout is no longer space allocated to it, it is the element of each side will be closed, on when he never existed. 

visibility: hidden hides the corresponding elements, but still retain the original layout of the space in the document. The difference in the link andimport CSS is?

CSS中 link 和@import 的辨别是？

The difference in the link andimport CSS is?

(1) link属于HTML标签，而@import是CSS供应的; 
(2) 页面被加载的时，link会同时被加载，而@import援用的CSS会比及页面被加载完再加载;
(3) import只在IE5以上才辨认，而link是HTML标签，无兼容题目; 
(4) link体式格局的款式的权重 高于@import的权重.

(1) link belong to HTML tags, and CSSimport is provided; 
(2) the page is loaded, link will also be loaded, but referencesimport CSS will wait until the page is finished loading reloading; 
(3) Import only to recognize in IE5 or more, while link is HTML tag, no compatibility issues; style right 
(4) linkimport way of weight above the weight of heavy. Similarities and Differences between absolute and float attributes: position

position:absolute和float属性的异同

Similarities and Differences between absolute and float attributes: position

A：共同点：
对内联元素设置`float`和`absolute`属性，可以让元素离开文档流，而且可以设置其宽高。

B：差别点：
float仍会占有位置，position会掩盖文档流中的其他元素。

A: common: 
inline element set `float` and` absolute` property allows elements from the document flow, and can set its width and height. 

B: Different point: 
float will still occupy the position, position overrides other elements in the document flow.

引见一下box-sizing属性？

Introduce the box-sizing property?

box-sizing属性主要用来掌握元素的盒模子的剖析形式。默许值是content-box。
box-sizing property is primarily used to control element analytical model box model. The default value is content-Box.

• content-box：让元素保持W3C的规范盒模子。元素的宽度/高度由border + padding + content的宽度/高度决议，设置width/height属性指的是content部份的宽/高
• content-Box : Let element to maintain the standard W3C box model. Width / height of the element / height is determined by the border + padding + content width, set width / height attribute refers to the content portion of the width / height
• border-box：让元素保持IE传统盒模子（IE6以下版本和IE6~7的奇异形式）。设置width/height属性指的是border + padding + content
• border-Box : Let element to maintain the traditional box model IE (IE6 and IE6 ~ 7 the following versions of quirks mode). Set width / height attribute refers to the border + padding + content

规范浏览器下，根据W3C范例对盒模子剖析，一旦修改了元素的边框或内距，就会影响元素的盒子尺寸，就不得不从新盘算元素的盒子尺寸，从而影响全部页面的规划。

Under standard browser, according to W3C box model specification analysis, once the border or modify the elements within distance, it will affect the size of the box element, you have to recalculate the box the size of the elements, thus affecting the layout of the entire page.

CSS 挑选符有哪些？哪些属机可以继续？优先级算法怎样盘算？ CSS3新增伪类有那些？

CSS selectors are there? Which attributes can be inherited? Priority algorithm calculated? Added CSS3 pseudo-classes are those?

1.id挑选器（ # myid）
2.类挑选器（.myclassname）
3.标签挑选器（div, h1, p）
4.相邻挑选器（h1 + p）
5.子挑选器（ul > li）
6.子女挑选器（li a）
7.通配符挑选器（ * ）
8.属性挑选器（a[rel = "external"]）
9.伪类挑选器（a: hover, li:nth-child）

1.id selector (# myid) 
2. Class selector (.myclassname) 
3. Tag selectors (div, h1, P) 
4. adjacent selector (h1 + P) 
5. child selector (ul> li ) 
6. descendant selectors (li a) 
7. wildcard selector (*) 
8. attribute selector (a [rel = "external"]) 
9. pseudo-class selectors (a: hover, li: nth-child)
      

• 可继续的款式： font-size font-family color, text-indent;

• 不可继续的款式：border padding margin width height ;

• 优先级就近准绳，同权重状况下款式定义近来者为准;

• 载入款式以末了载入的定位为准;
• Inheritable style: font-size font-family color, text-indent;
• Non Inherited Styles: border padding margin width height;
• Priority under the principle of proximity, with weights whichever the case recently defined style;

• Loading last loaded positioning styles to prevail;

优先级为:

Priority:

  
  
!important >  id > class > tag  
  
important 比 内联优先级高,但内联比 id 要高

CSS3新增伪类举例：

   
p:first-of-type 挑选属于其父元素的首个 <p> 元素的每一个 <p> 元素。
p:last-of-type  挑选属于其父元素的末了 <p> 元素的每一个 <p> 元素。
p:only-of-type  挑选属于其父元素唯一的 <p> 元素的每一个 <p> 元素。
p:only-child    挑选属于其父元素的唯一子元素的每一个 <p> 元素。
p:nth-child(2)  挑选属于其父元素的第二个子元素的每一个 <p> 元素。
:enabled  :disabled 掌握表单控件的禁用状况。
:checked        单选框或复选框被选中。

position的值， relative和absolute离别是相关于谁举行定位的？

position values, relative and absolute are positioned with respect to whom?

absolute 
        天生相对定位的元素， 相关于近来一级的 定位不是 static 的父元夙来举行定位。

fixed （老IE不支撑）
    天生相对定位的元素，相关于浏览器窗口举行定位。 

relative 
    天生相对定位的元素，相关于其在普通流中的位置举行定位。 

static  默许值。没有定位，元素涌如今一般的流中

absolute 
    generate absolute element positioned relative to the recent level is not static positioned parent element to be positioned. 

fixed (old IE does not support) 
    to generate absolute element positioned relative to the browser window positioning. 

relative 
    generating element relative positioning, relative to its position in the general stream positioning. 

static default. No positioning element occurs in the normal stream

CSS3有哪些新特征？

CSS3 What’s new?

CSS3完成圆角（border-radius），暗影（box-shadow），
对笔墨加殊效（text-shadow、），线性渐变（gradient），扭转（transform）
transform:rotate(9deg) scale(0.85,0.90) translate(0px,-30px) skew(-9deg,0deg);//扭转,缩放,定位,倾斜
增添了更多的CSS挑选器  多背景 rgba 
在CSS3中唯一引入的伪元素是::selection.
媒体查询，多栏规划
border-image

CSS3 rounded corners (border-radius), shadow (box-shadow), 
add special effects to the text (text-shadow,), a linear gradient (gradient), rotation (transform) 
transform: Rotate (9deg) Scale (0.85,0.90) translate (0px, -30px) skew (-9deg, 0deg); // rotation, scaling, positioning, tilt 
adds more CSS selectors more background rgba 
unique introduced in CSS3 pseudo-elements :: selection. 
Media queries , multi-column layout 
border-image
  

XML和JSON的辨别？

XML and JSON difference?

(1).数据体积方面。
JSON相关于XML来说，数据的体积小，通报的速率更快些。
(2).数据交互方面。
JSON与JavaScript的交互越发轻易，更轻易剖析处置惩罚，更好的数据交互。
(3).数据形貌方面。
JSON对数据的形貌性比XML较差。
(4).传输速率方面。
JSON的速率要远远快于XML。

(1) The data volume terms. 
XML JSON relative terms, the volume of data is small, the speed of delivery faster. 
(2) aspects of data exchange. 
JSON and JavaScript interaction more convenient and easier to parse processing, better data interaction. 
(3) The data described aspects. 
JSON description of data than XML poor. 
(4) The transmission speed. 
JSON's speed is much faster than XML.

对BFC范例的明白？

BFC norms of understanding?

      BFC，块级花样化高低文，一个创建了新的BFC的盒子是自力规划的，盒子内里的子元素的款式不会影响到外面的元素。在同一个BFC中的两个毗连的块级盒在垂直方向（和规划方向有关联）的margin会发作摺叠。
    （W3C CSS 2.1 范例中的一个观点，它决议了元素怎样对其内容举行规划，以及与其他元素的关联和相互作用。）
    BFC, block-level formatting context, a BFC created a new box is an independent layout, style, child elements inside the box will not affect the outside elements. In the same BFC two adjoining block-level box in the vertical direction (the direction of a relationship and layout) of margin will collapse from happening. 
    (A concept W3C CSS 2.1 specification, which determines how the elements in the layout of its contents, and its relationship with other elements and interactions.)

诠释下 CSS sprites，以及你要怎样在页面或网站中运用它。

Talk about your understanding of the semantic?

CSS Sprites实在就是把网页中一些背景图片整合到一张图片文件中，再利用CSS的“background-image”，“background- repeat”，“background-position”的组合举行背景定位，background-position可以用数字能准确的定位出背景图片的位置。如许可以削减许多图片要求的开支，由于要求耗时比较长；要求虽然可以并发，然则也有限定，平常浏览器都是6个。关于将来而言，就不须要如许做了，由于有了`http2`。
CSS Sprites in fact, the number of pages in the background image into an image file, and then use the CSS "background-image", "background- repeat", "background-position" a combination of background positioning, background-position can be used Digital can accurately locate the position of the background image. This can reduce the cost of many pictures request because the request takes a relatively long; although requests can be complicated, but there are limits, are six general browser. For the future, there is no need to do so, and because of `http2`.

html部份

html part

说说你对语义化的明白？

Talk about your understanding of the semantic?

1，去掉或许丧失款式的时刻可以让页面显现出清楚的构造
2，有利于SEO：和搜索引擎竖立优越沟通，有助于爬虫抓取更多的有用信息：爬虫依赖于标签来肯定高低文和各个关键字的权重；
3，轻易其他装备剖析（如屏幕阅读器、瞽者阅读器、挪动装备）以意义的体式格局来衬着网页；
4，便于团队开辟和保护，语义化更具可读性，是下一步吧网页的主要意向，遵照W3C规范的团队都遵照这个规范，可以削减差异化。

1, removed or lost when allowing page style showing clear structure 
2, is conducive to SEO: search engines and to establish good communication helps crawlers to crawl more useful information: reptiles rely on labels to determine the context and the individual right keyword weight; 
3, easy to resolve other devices (such as a screen reader, blind readers, mobile devices) in meaningful ways to render web pages;     4, easy to team development and maintenance, more readable semantic, is under Important Trends step right of the page, follow the W3C standards team follow this standard, the difference can be reduced.

Doctype作用? 严厉形式与混淆形式怎样辨别？它们有何意义?

Doctype role? Strict mode and mixed mode how to distinguish? They mean?

（1）、<!DOCTYPE> 声明位于文档中的最前面，处于 <html> 标签之前。示知浏览器以何种形式来衬着文档。 

（2）、严厉形式的排版和 JS 运作形式是  以该浏览器支撑的最高规范运转。

（3）、在混淆形式中，页面以宽松的向后兼容的体式格局显现。模仿老式浏览器的行动以防备站点没法事情。

（4）、DOCTYPE不存在或花样不正确会致使文档以混淆形式显现。  

(1), <! DOCTYPE> declaration in the document in the front, in the <html> tag before. Tells the browser to render the document in which mode. 

(2) strict mode layout and JS mode of operation is based on the highest standards of the browser supports running. 

(3), in promiscuous mode, page backward compatible with liberal display. Simulate the behavior of older browsers do not work to prevent the site. 

(4), DOCTYPE does not exist or incorrectly formatted document will lead to promiscuous mode rendering.   

你晓得若干种Doctype文档范例？

Do you know how many document types Doctype?

 该标签可声明三种 DTD 范例，离别示意严厉版本、过渡版本以及基于框架的 HTML 文档。
 HTML 4.01 划定了三种文档范例：Strict、Transitional 以及 Frameset。
 XHTML 1.0 划定了三种 XML 文档范例：Strict、Transitional 以及 Frameset。
Standards （规范）形式（也就是严厉显现形式）用于显现遵照最新规范的网页，而 Quirks
 （包涵）形式（也就是松懈显现形式或许兼容形式）用于显现为传统浏览器而设想的网页。
 
 The label can be declared DTD three types, respectively strict version, interim version and an HTML-based documentation framework. 
 HTML 4.01 specifies three document types: Strict, Transitional, and Frameset. 
 XHTML 1.0 specifies three XML document types: Strict, Transitional, and Frameset. 
 Standards (standard) mode (that is, in strict rendering mode) complies with the latest standards for rendering Web pages, while Quirks 

(inclusive) mode (that is, loose rendering mode or compatibility mode) is used to render conventional web browser designed.

HTML与XHTML——两者有什么辨别

HTML and XHTML– What is the difference

辨别：
1.一切的标记都必须要有一个响应的完毕标记
2.一切标签的元素和属性的名字都必须运用小写
3.一切的XML标记都必须合理嵌套
4.一切的属性必须用引号""括起来
5.把一切<和&特殊标记用编码示意
6.给一切属性赋一个值
7.不要在解释内容中使“--”
8.图片必须有申明笔墨

Difference: 
1. All tags must have a corresponding end tag element and attribute names 
2. All tags must be lowercase 
3. All the XML tags must be properly nested 
4. All attributes must be quoted. " "enclosed 
5. Put all the <and & special symbols with the coded representation 
6. assign a value to all of the properties in the comment 7. Do not manipulation "-" 
8. The image must have caption

罕见兼容性题目？

Common compatibility problems?

* png24位的图片在iE6浏览器上涌现背景，处理方案是做成PNG8.也可以援用一段剧本处置惩罚.

* 浏览器默许的margin和padding差别。处理方案是加一个全局的*{margin:0;padding:0;}来一致。

* IE6双边距bug:块属性标签float后，又有横行的margin状况下，在ie6显现margin比设置的大。 

* 浮动ie发生的双倍间隔（IE6双边距题目：在IE6下，假如对元素设置了浮动，同时又设置了margin-left或margin-right，margin值会更加。）
  #box{ float:left; width:10px; margin:0 0 0 100px;} 

 这类状况之下IE会发生20px的间隔，处理方案是在float的标签款式掌握中到场 ——_display:inline;将其转化为行内属性。(_这个标记只要ie6会辨认)

*  渐进辨认的体式格局，从整体中逐步消除部分。 

* Png24 bit image appears on iE6 browser background, the solution is made ​​PNG8. It can refer to a script processing. 

* The browser's default margin and padding. The solution is to add a global * {margin: 0; padding: 0;} to unify. 

* IE6 bilateral Distance bug: After the block attribute labels float, there are rampant margin circumstances, in ie6 show larger margin than the settings. 

* Double ie generated from the float (IE6 bilateral distance problem: In IE6, if the element is set to float, while setting the margin-left or margin-right, margin value will double.) 

#box {float: left; width: 10px; margin: 0 0 0 100px;}

Under such circumstances IE will produce 20px distance, the solution is to add –_ display in the label style float control: inline; be converted to inline property. (_ This symbol identifies only ie6)

* gradual recognition of the way from the local population gradually excluded. 

  起首，奇妙的运用“\9”这一标记，将IE游览器从一切状况中星散出来。 
  接着，再次运用“+”将IE8和IE7、IE6星散开来，如许IE8已自力辨认。
  
  First, the clever use of "\ 9" This marks the IE's browser separated out from all the circumstances. 
  Then, again using the "+" to IE8 and IE7, IE6 separated, so that IE8 has been independently identified. 

  css
      .bb{
       background-color:#f1ee18;/*一切辨认*/
      .background-color:#00deff\9; /*IE6、7、8辨认*/
      +background-color:#a200ff;/*IE6、7辨认*/
      _background-color:#1e0bd1;/*IE6辨认*/ 
      } 

*  IE下,可以运用猎取通例属性的要领来猎取自定义属性,
   也可以运用getAttribute()猎取自定义属性;
   Firefox下,只能运用getAttribute()猎取自定义属性. 
   处理要领:一致经由过程getAttribute()猎取自定义属性.

* IE下,event对象有x,y属性,然则没有pageX,pageY属性; 
  Firefox下,event对象有pageX,pageY属性,然则没有x,y属性.

* 处理要领：（前提解释）瑕玷是在IE浏览器下可能会增添分外的HTTP要求数。

* Chrome 中文界面下默许会将小于 12px 的文本强迫根据 12px 显现, 
  可经由过程到场 CSS 属性 -webkit-text-size-adjust: none; 处理.

* 超链接接见事后hover款式就不涌现了 被点击接见过的超链接款式不在具有hover和active了处理要领是转变CSS属性的分列递次:
L-V-H-A :  a:link {} a:visited {} a:hover {} a:active {}

* 奇异形式题目：漏写DTD声明，Firefox仍然会根据规范形式来剖析网页，但在IE中会触发奇异形式。为防备奇异形式给我们带来不必要的贫苦，最好养成誊写DTD声明的好习气。如今可以运用[html5](http://www.w3.org/TR/html5/single-page.html)引荐的写法：`<doctype html>`

* 高低margin重合题目
ie和ff都存在，相邻的两个div的margin-left和margin-right不会重合，然则margin-top和margin-bottom却会发作重合。
处理要领，养成优越的代码编写习气，同时采纳margin-top或许同时采纳margin-bottom。
* ie6对png图片花样支撑不好(援用一段剧本处置惩罚)

* under IE, you can use the method to get the general properties for custom properties, 

you can also use getAttribute () Gets the custom attributes;
under Firefox, only Use getAttribute () Gets custom attributes.
Workaround: Uniform for custom properties through getAttribute ().

* Under IE, event object has x, y attributes, but no pageX, pageY property; 

under Firefox, event object has pageX, pageY property, but there is no x, y properties.

* Solution :( conditional comments) drawback is that in IE browser may add additional HTTP requests. 

* Under Chrome Chinese interface will be smaller than default to force the 12px 12px text display, 

by the addition of CSS properties -webkit-text-size-adjust: none; resolved.

* After hover style is not accessible by hyperlink is clicked appears visited The Hyperlink style does not have hover and active the solution is to change the order of CSS properties: 

LVHA: a: link {} a: visited {} a: hover {} a: Active {}

* weird modalities: Leakage write DTD statement, Firefox will still be in accordance with the standard model to resolve the page, but IE will trigger quirks mode. To avoid quirks mode gives us unnecessary trouble, it is best to develop the good habit of writing DTD declaration. You can now use [html5] (http://www.w3.org/TR/html5/single-page.html) recommended notation: `<DOCTYPE html>` 

* top and bottom margin overlap problem 

ie and ff are present, adjacent both margin-left and margin-right does not coincide div, but margin-top and margin-bottom but it will coincide occur.
Solution, to develop good coding habits, while using margin-top or while using margin-bottom.

* Ie6 png image format support is not good for (quote a script processing)

诠释下浮动和它的事情道理？消灭浮动的技能

Floating and explain how it works? Clear float tips

浮动元素离开文档流，不占有空间。浮动元素遇到包括它的边框或许浮动元素的边框停止。
Floating elements from the document flow, does not occupy space. Floats across the border to stay its borders contain or floating elements. 

1.运用空标签消灭浮动。
   这类要领是在一切浮动标签背面增加一个空标签 定义css clear:both. 弊病就是增添了无意义标签。
2.运用overflow。
   给包括浮动元素的父标签增加css属性 overflow:auto; zoom:1; zoom:1用于兼容IE6。
3.运用after伪对象消灭浮动。
   该要领只适用于非IE浏览器。详细写法可参照以下