bem. what you can borrow from yandex frontend dev
Post on 18-Dec-2014
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Frontend developer
BEMWhat you can borrow from Yandex frontend dev
Varvara Stepanova
Over 80 services
• search– web pages– images, video– goods, news, blog posts, people
• web mail• web maps
– traffic jams, wiki maps, taxi• hosting and sharing
– files, photos, video
5
Inside Yandex
• 2500 developers• 150+ frontend developers
6
Dark side of the Force
Programming is a team work
Developers community
We do enjoy sharing
Web Interface
Behind the page
13
CSS
body { font: 0.8em Arial, sans-serif; margin: 0; color: black;}.sidebar ul li {
HTML
<!DOCTYPE html><html> <head>...</head> <body> ... </body>
Block
Menu block
20
HTML
<ul class="menu"> <li><a href="/new">New titiles</a></li> <li><a href="/soon">Coming soon</a></li> <li><a href="/best">Bestsellers</a></li> ...
CSS
.menu { list-style: none;
Search block
2120
HTML
<div class="search"> <input type="text" name="search" value="..."/> <input type="button" name="sbmt" value="Search"/></div>
CSS
.search { padding: 2em 0;
Tabbed pane block
22
HTML
<div class="tabbed-pane"> <ul> <li>Bestsellers</li><li>...</li> </ul> <div> The Casual Vacancy, J.K. Rowling </div></div>
CSS
.tabbed-pane { margin: 0.5em; ...}
INDEPENDENT
index.html
<!DOCTYPE html><html> <head>..</head> <body>
<div class="head"> <div class="logo">...</div> <ul class="menu">...</ul> <div class="search">...</div> </div>
<div class="layout">...</div>
<div class="foot">...</div>
</body></html>
The page of blocks
24
Repeating
Menu block
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HTML<ul id="menu"> ...
HTML<ul class="menu"> ...
CSS#menu { ...
CSS.menu { ...
Block is independent, if
• a block has its "name"–no "id" but "classname" selectors
• avoids cascade• no "tag" selectors
28
Movement within a Page
Block is independent, if
• a block has its "name"–no "id" but "classname" selectors
• avoid cascade• no "tag" selectors
31
almost NO CASCADEwhen using Cascading Style Sheets
32
Moving within a Site
index page
Pages are sets of blocks
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search page contacts page
CSS for different pages
41
common.css
body { ... }
.head { ... }
.head ul li { ...}
a:link, ... {}
index.css
.advert { ... }
.layout .books { ...}
contacts.css
body .phone { ...}
.phone a { ...}
#map {}
style.css
body { ... }.head { .. }.head ul li { ... }a:link, ... { ... }.advert { ... }.layout .books { ... }body .phone { ... }.phone a { ... }#map { ... }
index page
Pages are sets of blocks
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search page contacts page
blocks/ header.css menu.css button.css tabbed-pane.css logo.css footer.css
CSS for every block
45
index.css
@import url(blocks/header.css);@import url(blocks/menu.css);@import url(blocks/tabbed-pane.css);@import url(blocks/text.css);@import url(blocks/logo.css);@import url(blocks/footer.css);...
CSS for a page
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blocks/
advert.css books-list.css head.css foot.css logo.css menu.css search.css tabbed-pane.css
pages/
index.html index.css
contacts.html contacts.css
book.html book.css
Project file system
47
WE NEED TO GO
DEEPER
Inside a Block
Menu block
50
HTML
<ul class="menu"> <li><a href="/new">New titles</a></li> <li><a href="/soon">Coming soon</a></li> <li><a href="/best">Bestsellers</a></li> ...</ul>
Menu block
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blocks/menu.css
.menu li{ list-style: none; display: inline-block; padding: 0 0.5em;}
Menu and Dropdown blocks
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blocks/menu.css.menu li{ list-style: none; display: inline-block; padding: 0 0.5em;}
pages/index.html<li> <a href="#">Bestsellers</a> <div class="dropdown"> <ul> <li>Item One</li> <li>Item Two</li> <li>The best item</li> <li>Item Three</li>
Block is independent, if
• a block has its "name"–no "id" but "classname" selectors
• avoid cascade• no "tag" selectors
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The style system matches rules by starting with the key selector, then moving to the left (looking for any ancestors in the rule’s selector).
David Hyatt, MDN
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mzl.la/UuwZql
.menu li {
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.menu li {
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Menu block
57
Element
Elements
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Search block
60
Tabbed-pane block
61
Menu
62
page.html
<ul class="menu"> <li class="menu__item"><a href="/">Index</a></li> <li class="menu__item"><a href="/new">New</a></li> <li class="menu__item"><a href="/offer">Special offer</a></li> <li class="menu__item"><a href="/shipping">Shipping</a></li></ul>
Menu
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.tabbed-pane__tab
.block-element
.block--element
.block___element
blocks/menu.css
.menu li{ list-style: none; display: inline-block; padding: 0 0.5em;}
Optional elements
64
blocks/
search.css search__checkbox.css search__autocomlete.css
tabbed-pane.css tabbed-pane__tab.css tabbed-pane__pane.css
menu.css menu__item.css
book.css book__title.css book__image.css
Files for elements
65
Modifier
Similar but different
67
HTML
<div class="tabbed-pane tabbed-pane_theme_blue"> <ul> <li class="tabbed-pane__tab">Tab 1</li> <li class="tabbed-pane__tab">Tab 2</li> </ul> <div class="tabbed-pane__pane"> ... </div></div>
Modifier
68
HTML
<div class="tabbed-pane tabbed-pane_theme_blue tabbed-pane_direction_bottom"> ...</div>
<input class="button button_theme_black button_size_l" ... />
Modifier
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tabbed-pane_theme_bluetabbed-pane_theme_white
tabbed-pane_size_stabbed-pane_size_l
button_size_sbutton_size_l
block-name_mod-name_mod-val
70
blocks/
tabbed-pane.css tabbed-pane__tab.css tabbed-pane__pane.css tabbed-pane_theme_blue.css tabbed-pane_theme_black.css tabbed-pane_direction_bottom.css
Block files structure
71
CSS
@import url(blocks/header.css);@import url(blocks/search.css);@import url(blocks/tabbed-pane.css);@import url(blocks/tabbed-pane__tab.css);@import url(blocks/tabbed-pane__pane.css);@import url(blocks/tabbed-pane_theme_blue.css);@import url(blocks/button.css);@import url(blocks/logo.css);@import url(blocks/footer.css);
Taken when necessary
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Modifiers for elements
73
CSS
<div class="tabbed-pane"> <span class=" tabbed-pane__tab tabbed-pane__tab_state_current">...</span></div>
Taken when necessary
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Block modifier DO affects elements
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CSS
.tabbed-pane_theme_blue
.tabbed-pane__tab{ background-color: #9CF;}
Cascade is possible
76
Block File Structure
blocks/
tabbed-pane.css tabbed-pane__tab.css tabbed-pane__pane.css tabbed-pane_theme_blue.css tabbed-pane_theme_black.css tabbed-pane_size_l.css tabbed-pane_size_s.css
menu.css menu__item.css menu_size_l.css menu_size_s.css
logo.css search.css search__checkbox.css search__autocomplete.css
File structure. The flat case
78
blocks/
tabbed-pane/ tabbed-pane.css tabbed-pane__tab.css tabbed-pane__pane.css tabbed-pane_theme_blue.css tabbed-pane_theme_black.css tabbed-pane_size_l.css tabbed-pane_size_s.css
logo/ logo.css
menu/ menu.css menu__item.css menu_size_l.css menu_size_s.css
search/ search.css search__checkbox.css search__autocomplete.css
File structure. Block folder
79
blocks/
tabbed-pane/ __tab/ _state/ tabbed-pane__tab_state_current.css tabbed-pane__tab.css __pane/ tabbed-pane__pane.css _theme/ tabbed-pane_theme_blue.css tabbed-pane_theme_black.css tabbed-pane.css
File structure. Yandex way
80
BEM entities
• Block– combined in different ways– included one into another– independent
• Element• Modifier
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BEM is
• Methodologyis a way of thinking when developing
• Toolsdo monkey job for you
• Block librariesmake you develop faster and better
83
IE
HTML
<html> <head> <!--[if gt IE 7]><!--> <link rel="stylesheet" href="index.css"> <!--<![endif]--> <!--[if lt IE 8]> <link rel=stylesheet href="index.ie.css"> <![endif]--> </head> ...
Render to IE the things that are IE's
85
HTML
<html> <head> <!--[if gt IE 7]><!--> <link rel="stylesheet" href="index.css"> <!--<![endif]--> <!--[if lt IE 8]> <link rel=stylesheet href="index.ie.css"> <![endif]--> </head> ...
Render to IE the things that are IE's
86
CSS
@import url(index.css);@import url(blocks/menu/menu.ie.css);@import url(blocks/button/button.ie.css);@import url(blocks/footer/footer.ie.css);
CSS file for IE
87
CSS
@import url(index.css);@import url(blocks/menu/menu.ie.css);@import url(blocks/button/button.ie.css);@import url(blocks/footer/footer.ie.css);
CSS file for IE
88
blocks/
tabbed-pane/ tabbed-pane.css tabbed-pane.ie.css ...
menu/ menu.css menu.ie.css
Block files for IE
89
blocks/
tabbed-pane/ tabbed-pane.css tabbed-pane.ie.css tabbed-pane__item.css tabbed-pane__item.ie.css tabbed-pane_theme_blue.css tabbed-pane_theme_blue.ie.css
Element files for IE
90
Block encapsulates all
91
blocks/ menu/ menu__item.css menu__item.ie.css menu.css menu.ie.css
@import...@import...@import...@import...@import...@import...
index.css
@import...@import...@import...@import...@import...@import...
index.ie.css
JavaScript
Tabbed-pane block
94
Dropdown block
95
Dropdown block
96
index.html
<!DOCTYPE html><html> <head> <link rel=stylesheet href="index.css"> <script type="text/javascript" src="all.js"/> </head> ...
Page with JavaScript
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index.html
<!DOCTYPE html><html> <head> <link rel=stylesheet href="index.css"> <script type="text/javascript" src="index.js"/> </head> ...
Page with JavaScript
98
index page
Pages are sets of blocks
99
search page contacts page
blocks/ menu/ menu.css menu.js dropdown/ dropdown.css dropdown.js tabbed-pane/ tabbed-pane.css tabbed-pane.js
JavaScript for blocks
100
index.js
borschik:include:blocks/menu/menu.jsborschik:include:blocks/tabbed-pane/tabbed-pane.js...
Page JavaScript of blocks
101
index.js
/* Menu block begins */(function($){ $('.menu__item').on('click', function(e) { $(this).toggleClass('menu__item_state_current'); });})(jQuery)
git.io/borschik
Borschik — CSS&JS flattening
102
index.css
@import url(blocks/header.css);@import url(blocks/menu.css);...
CSS flatenning
103
_index.css
.header { ...}.menu { ...}
Relative paths in CSS
104
pages/_index.css
.menu {
background: url(../blocks/menu/menu__bg.png);
}
blocks/menu/menu.css.menu {
background: url(menu__bg.png);
}
pages/index.css@import url(blocks/menu/menu.css);
105
HTML<!DOCTYPE html><html> <head> <title>Awesome online bookshop</title> <link rel="stylesheet" href="style.css"/> <script type="text/javascript" src="magic.js"></script> </head> <body> <div class="head"> <ul class="menu"> <li class="menu__item"><a href="/">Home</a></li> <li class="menu__item"><a href="/news">News</a></li> ... </ul> <div class="phone">+3 71 1234567</div> </div> <div class="layout"> ... </div> </body></html>
general CSS@import url(blocks/head/head.css);@import url(blocks/search/search.css);@import url(blocks/layout/layout.css);@import url(blocks/menu/menu.css);@import url(blocks/text/text.css);@import url(blocks/foot/foot.css);
CSS for IE@import url(index.css);@import url(blocks/menu/menu.ie.css);@import url(blocks/text/text.ie.css);@import url(blocks/foot/foot.ie.css);
JavaScript(function($){
$('.menu__item').on('click', function() {
$(this).toggleClass('menu__item_state_current');
});})(jQuery)
Building Page Files
index.xml
<b:page> <b:head> <b:logo/> <b:search> <e:input/> <e:button/> </b-search> <b:menu> <e:item>Home</e:item> <e:item>Contacts</e:item> ...
Page declaration
108
index.bemjson
{ block: 'page', content: [ { block: head, content: [ { block: 'logo' }, { block: 'search', ....
Page declaration. BEM tree
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Change BEM tree if you need changes
110
page.htmlpage.csspage.js}
git.io/bem-tools
BEM tools build pages with blocks
111
blocks/
menu/ menu.sass menu.less menu.coffee
tabbed-pane/ tabbed-pane.sass tabbed-pane.coffee
pages/
index.htmlindex.sass -> index.cssindex.coffee -> index.js
BEM tools support many technologies
112
blocks/
menu.css menu_theme_black.css menu_theme_blue.css menu_size_l.css menu_size_s.css menu-item.css menu-item_state_current.css
tabbed-pane.css tabbed-pane_theme_black.css tabbed-pane_theme_blue.css tabbedpane-item.css tabbedpane-pane.css
logo.css
BEM tools support any file structure
113
blocks/
menu/ __item/ menu__item.css _theme/ menu_theme_black.css menu_theme_blue.css _size/ menu_size_l.css menu_size_s.css menu.css
tabbed-pane/
logo/
Multilingual
blocks/
menu/ tabbed-pane.css tabbed-pane.js tabbed-pane.md
BEM tools support custom technologies
115
blocks/
menu/ tabbed-pane.css tabbed-pane.js tabbed-pane.md tabbed-pane.xsl
BEM tools support custom technologies
116
Gruelling race... every day
blocks/
menu/ tabbed-pane.css tabbed-pane.js tabbed-pane.md tabbed-pane.bemhtml
BEMHTML template engine
118
bit.ly/bemhtml-doc-raw
BEMHTML reference [RU]
119
Libraries
Block libraries
121
Block page and block examples
123
Block code on GitHub
124
git.io/bootstrap-bl
git.io/jqueryui-bl
git.io/modernizr-bl
Libraries with BEM stack
125
Wanna try?
git.io/bem-project-stub
BEM-based project
127
Dev Tools
git.io/borschik
Borschik — CSS & JS flattening
129
bem.info/tools/csso
CSS Optimizer
130
BEFORE.test1 { border: none; background-color: red;}
.test2 { border: none}
.test3 { background-color: #FF000;}
AFTER.test1, .test2 { border: none}
.test1, .test3 { background-color: #F00;}
git.io/svgo
SVG Optimizer
131
Varvara StepanovaVladimir VarankinFrontend developers
varankinv@yandex-team.ru@toivonens@tvii
@bem_tw
Thank you
toivonen@yandex-team.ru
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