位置: 编程技术 - 正文

CSS对Web页面载入效率的影响分析总结(网页css加载失败)

编辑:rootadmin
我们罗列了十几条相关的知识与注意点,大家可以系统的探讨一下,让我们编写的Web页面打开更加流畅。   请不要告诉我,你看不懂E文,只是你不愿意看!!!   1、How the style system breaks up rules   The style system breaks rules up into four primary categories. It is critical to understand these categories, as they are the first line of defense as far as rule matching is concerned. I use the term key selector in the paragraphs that follow. The key selector is defined to be the rightmost occurrence of an id selector, a class selector, or a tag selector.   1.1、ID Rules   The first category consists of those rules that have an ID selector as their key selector. button#backButton { } /* This is an ID-categorized rule */ #urlBar[type="autocomplete"] { } /* This is an ID-categorized rule */ treeitem > treerow > treecell#myCell :active { } /* This is an ID-categorized rule */   1.2、Class Rules If a rule has a class specified as its key selector, then it falls into this category. button.toolbarButton { } /* A class-based rule */ .fancyText { } /* A class-based rule */ menuitem > .menu-left[checked="true"] { } /* A class-based rule */   1.3、Tag Rules   If no class or ID is specified as the key selector, then the next potential category for a rule is the tag category. If a rule has a tag specified as its key selector, then the rule falls into this category. td { } /* A tag-based rule */ treeitem > treerow { } /* A tag-based rule */ input[type="checkbox"] { } /* A tag-based rule */   1.4、Universal Rules   All other rules fall into this category. :table { } /* A universal rule */ [hidden="true"] { } /* A universal rule */ * { } /* A universal rule */ tree > [collapsed="true"] { } /* A universal rule */   2、How the Style System Matches Rules   The style system matches a rule by starting with the rightmost selector and moving to the left through the rule's selectors. As long as your little subtree continues to check out, the style system will continue moving to the left until it either matches the rule or bails out because of a mismatch.   Your first line of defense is the rule filtering that occurs based on the type of the key selector. The purpose of this categorization is to filter out rules so that you don't even have to waste time trying to match them. This is the key to dramatically increasing performance. The fewer rules that you even have to check for a given element, the faster style resolution will be. As an example, if your element has an ID, then only ID rules that match your element's ID will be checked. Only class rules for a class found on your element will be checked. Only tag rules that match your tag will be checked. Universal rules will always be checked.   3、Guidelines for Efficient CSS   3.1、Avoid Universal Rules!   Make sure a rule doesn't end up in the universal category!   3.2、Don't qualify ID-categorized rules with tag names or classes   If you have a style rule that has an ID selector as its key selector, don't bother also adding the tag name to the rule. IDs are unique, so you're slowing down the matching for no real reason.   3.3、Don't qualify class-categorized rules with tag names   Similar to the rule above, all of our classes will be unique. The convention you should use is to include the tag name in the class name.   3.4、Try to put rules into the most specific category you can!   The single biggest cause of slowdown in our system is that we have too many rules in the tag category. By adding classes to our elements, we can further subdivide these rules into class categories, and then we no longer waste time trying to match as many rules for a given tag. BAD - treeitem[mailfolder="true"] > treerow > treecell { } GOOD - .treecell-mailfolder { }   3.5、Avoid the descendant selector!   The descendant selector is the most expensive selector in CSS. It is dreadfully expensive, especially if a rule using the selector is in the tag or universal category. Frequently what is really desired is the child selector. The use of the descendant selector is banned in UI CSS without the explicit approval of your skin's module owner. BAD - treehead treerow treecell { } BETTER, BUT STILL BAD (see next guideline) - treehead > treerow > treecell { }   3.6、Tag-categorized rules should never contain a child selector!   Avoid using the child selector with tag-categorized rules. You will dramatically increase the matching time (especially if the rule is likely to be matched more often than not) for all occurrences of that element. BAD - treehead > treerow > treecell { } BEST - .treecell-header { }   3.7、Question all usages of the child selector!   Be careful about using the child selector. If you can come up with a way to avoid having to use it, do so. In particular, the child selector is frequently used with RDF trees and menus like so. BAD - treeitem[IsImapServer="true"] > treerow > .tree-folderpane-icon { }   Remember that attributes from RDF can be duplicated in a template! Take advantage of this fact to duplicate RDF properties on child XUL elements that wish to change based off that attribute. GOOD - .tree-folderpane-icon[IsImapServer="true"] { }   3.8、Rely on inheritance!   Learn which properties inherit, and allow them to do so! We have explicitly set up XUL widgetry so that you can put list-style-image (just one example) or font rules on the parent tag, and it will filter in to the anonymous content. You don't have to waste time writing a rule that talks directly to the anonymous content. BAD - #bookmarkMenuItem > .menu-left { list-style-image: url(blah); } GOOD - #bookmarkMenuItem { list-style-image: url(blah); }   In the above example, the desire to style the anonymous content (without understanding that list-style-image inherits) resulted in a rule that was in the class category, when this rule really should have ended up being in the most specific category of all, the ID category.   Remember, especially with anonymous content, that they all have the same classes! The bad rule above causes the icon of every menu to be checked to see if it is contained in the bookmarks menu item. This is hideously expensive (since there are many menus); this rule never should have even been checked by any menu other than the bookmarks menu.   3.9、Use -moz-image-region!   Putting a bunch of images into a single image file and selecting them with -moz-image-region performs significantly better than putting each image into its own file.   Original Document Information - Author: David Hyatt

推荐整理分享CSS对Web页面载入效率的影响分析总结(网页css加载失败),希望有所帮助,仅作参考,欢迎阅读内容。

CSS对Web页面载入效率的影响分析总结(网页css加载失败)

文章相关热门搜索词:网站css加载不出来,css加载,web中css,网站css加载不出来,网页css加载失败,页面引入css,网页css加载失败,css加载,内容如对您有帮助,希望把文章链接给更多的朋友!

巧妙地使用CSS选择器 可以通过不同规则来定义不同内容块里的链接样式。类似这样:#nava:link或者#maina:link或者#footera:link。也可以定义不同内容块中相同元素的样式不一样。

去除链接元素的虚线框 兼容IE7、IE6、FF 推荐下面的代码a{outline:none;/*forForefox*/}a{star:expression(this.onFocus=this.blur());/*forIe*/}下面的代码比较麻烦我们采用htc文件的办法来解决这个问题。首页将以

DIV border边框显示不完全问题的解决方法 第一次遇到这样的问题,就是定义div的边框有部分却显示不了。而在firefox里却是一切正常,该死的ie,太过分了。代码也没有问题,查了好多资料,还

标签: 网页css加载失败

本文链接地址:https://www.jiuchutong.com/biancheng/375269.html 转载请保留说明!

上一篇:提高CSS文件可维护性的五种方法总结(提高css文件可维性的方法)

下一篇:巧妙地使用CSS选择器(css选择器怎么写)

  • 丢失增值税专用发票最新规定
  • 应交税费课程
  • 月初没报完税可以开票吗
  • 合伙企业每年费用
  • 个税系统设置在哪里
  • 举例说明税收支出的形式
  • 客户回款扣除的手续费会计分录怎么做?
  • 对外捐赠衣物怎样入账
  • 资本公积可以只给一个股东转增资本
  • 个税手续费返还会计分录
  • 退税显示未完成怎么处理
  • 小规模纳税人季报还是月报?
  • 滞留发票的税收处理
  • 文化建设服务费减免
  • 压缩包损坏修复软件
  • windows所有应用
  • 鸿蒙系统怎么开发
  • 使用U盘安装win7出现找不到任何设备驱动程序
  • 为什么电脑连上蓝牙耳机却是外放
  • php怎么学
  • php中split
  • 企业投资入股的几种方式
  • 计提企业所得税会计分录怎么做
  • php教程100
  • 前端页面默认字体
  • 存货包括哪些会计账户
  • element栅格布局
  • 委托加工物资增值税计税依据
  • 上月未开发票的销项税,已经申报缴税,在本月开了票,应该如何填报?
  • Yii2 rbac权限控制之rule教程详解
  • 购买电脑如何入账
  • 税收优惠会计分录 附加税
  • javaweb实验一
  • vue点击按钮显示对应的内容
  • 微信小程序开发零基础入门
  • 基建拨款会计分录
  • 固定资产一次性折旧账务处理
  • 预付账款的会计处理
  • php 队列
  • 保险费计入固定资产原值吗
  • 不抵扣的进项税额用不用转出
  • sql2005备份数据库
  • 十个提高情商的方法
  • sql聚合语句
  • SqlServer中用exec处理sql字符串中含有变量的小例子
  • 深圳市企业稳岗补贴标准
  • 电子发票查询真伪
  • 通货膨胀有什么表现
  • 出口收汇核销单的作用
  • 法院强制执行根本没用
  • 其他债权投资的特征有哪些
  • 原材料存货跌价准备
  • 长期股权投资两种核算方法的区别
  • 中央空调的维护费一年要多少钱?
  • sql server 错误
  • sql返回一条数据
  • win8系统中断怎么解决
  • win2003加速开机
  • 提高系统能力
  • archlinux安装教程2023 无线网络
  • bd是什么文件
  • rhel7
  • directx?
  • 如何打开和关闭HMB
  • 微软发布Win10优化工具
  • pap是什么文件
  • window10升级不了
  • linux 日历
  • android openconnect
  • css中hack
  • shell脚本运行linux命令
  • python3并发
  • 反序存放字符串
  • 基于JAVASCRIPT实现的可视化工具是
  • javascript题
  • jquery可以实现哪些效果
  • js cookie用法
  • The method findViewById(int) is undefined for the type FragmentHome报错
  • 个人所得税完税证明
  • 泰兴市税务局办税服务厅
  • 免责声明:网站部分图片文字素材来源于网络,如有侵权,请及时告知,我们会第一时间删除,谢谢! 邮箱:opceo@qq.com

    鄂ICP备2023003026号

    网站地图: 企业信息 工商信息 财税知识 网络常识 编程技术

    友情链接: 武汉网站建设