Modular CSS v2 (CSS-in-JS edition)

Slides of my evolved "Modular CSS" talk from React Alicante

Transcript

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2. Thanks to our sponsors!
   

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3. Andrey Okonetchnikov
   @okonetchnikov
   

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5. ColorSnapper
   http://colorsnapper.com
   

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7. Past Current time Future
   

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8. A brief history of CSS
   

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9. CSS 1.0
   Present Future
   CSS 2.1 Proposed
   1996 2004
   

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10. Present Future
    1996 2004
    

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11. CSS was designed for
    documents
    

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12. How many of you have ever re-designed
    a web-site with CSS changes only?
    ✋
    

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13. Present Future
    1996 2004
    

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14. Present Future
    1996 2004 2005
    

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15. 2005 Present Future
    1996 2004
    

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19. Web-applications are built
    with UI Components
    

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20. UI Components
    Button
    

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21. Button
    UI Components
    

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22. 20+ years since the release
    of CSS 1.0
    

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23. CSS was designed for documents,
    not for web-applications
    

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24. Best practices
    

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25. Separation of concerns
    

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26. Separation of concerns
    JS
    CSS
    HTML
    

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27. Separation of concerns
    JS
    CSS
    HTML
    Checkbox
    Button
    Dropdown
    List
    Modal
    

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29. Natural mapping
    

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30. Natural mapping
    

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31. Past Current time Future
    

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32. HTML-in-JS
    a.k.a. JSX
    

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37. https://trends.google.com/trends/explore?q=%2Fm%2F012l1vxv,
    %2Fm%2F0268gyp
    

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39. Everything is a component!
    

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40. f(state) => UI
    

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41. What about styles?
    

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42. • Logic
    • HTML
    • Styles
    Button
    • Logic
    • HTML
    • Styles
    • Logic
    • HTML
    • Styles
    

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43. • Logic
    • HTML
    • Styles
    Button
    • Logic
    • HTML
    • Styles
    • Logic
    • HTML
    • Styles
    Global styles
    

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44. • Logic
    • HTML
    • Styles
    Button
    • Logic
    • HTML
    • Styles
    • Logic
    • HTML
    • Styles
    Global styles
    

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45. View Slide

46. Global CSS
    1 .btn {
    2 /* styles for button */
    3 }
    4
    5 .active {
    6 /* styles for active button */
    7 background-color: blue;
    8 }
    9
    10 .label {
    11 /* styles for button label */
    12 }
    1 .star {
    2 /* styles for star */
    3 }
    4
    5 .active {
    6 /* styles for active star
    7 background-color: orange;
    8 }
    9
    
    

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47. .btn.active
    

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48. .content .albums .btn.active
    

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50. View Slide

51. BEM
    https://en.bem.info/
    

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52. B
    E
    M
    

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53. .Block
    .Block --element
    .Block --element __modifier
    Block
    Element
    Modifier
    

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54. BEM
    
    
    Click me!
    
    
    

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55. BEM
    
    
    Click me!
    
    
    

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56. Manual work
    

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57. 
    
    One
    
    
    Two
    
    
    Three
    
    
    

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58. .nav __item {
    padding: 4px 10px;
    color: black;
    }
    .nav __item_active {
    font-weight: bold;
    background: #ffc7c7;
    }
    .navigation __item {
    padding: 4px 10px;
    color: black;
    }
    .navigation __item_active {
    font-weight: bold;
    background: #ffc7c7;
    }
    

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61. Manual work
    

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63. +
    

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64. https://github.com/css-modules/css-modules
    

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65. Before: BEM-style
    const Button = ({ children }) => (
    
    
    { children }
    
    
    )
    

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66. After: CSS-modules
    import styles from './Button.css'
    const Button = ({ children }) => (
    
    
    { children }
    
    
    )
    

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67. After: CSS-modules
    import styles from './Button.css'
    const Button = ({ children }) => (
    
    
    { children }
    
    
    )
    

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68. How CSS-modules work?
    

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69. Before: BEM-style
    /* Button.css */
    .Button { /* general rules */ }
    .Button --disabled { /* disabled rules */ }
    .Button --active { /* active rules */ }
    .Button __label { /* label rules */ }
    

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70. After: CSS-modules
    /* Button.css */
    .root { /* general rules */ }
    .disabled { /* disabled rules */ }
    .active { /* active rules */ }
    .label { /* label rules */ }
    

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71. The result
    1 styles: {
    2 root: "Button __root __abc5436",
    3 disabled: "Button __disabled __def65
    4 active: "Button __active __1638bcd",
    5 label: "Button __label __5dfg462"
    5 }
    1 /* Button.css */
    2
    3 .root { }
    4 .disabled { }
    5 .active { }
    6 .label { }
    

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72. CSS-modules
    import styles from './Button.css'
    const Button = ({ children }) => (
    
    
    { children }
    
    
    )
    

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73. BEM for free!
    ❤
    

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74. CSS-modules
    ✅ Explicit imports
    ✅ Scoped & fast selectors
    ✅ True rules isolation
    ✅ Code reuse, expressiveness
    ✅ Framework agnostic
    Non standard syntax
    (compose, vals, etc.)
    Build step is required
    No dead code elimination
    No automatic vendor prefixing
    

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76. +
    

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77. https://cssinjs.org
    

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78. export const styles = {
    button: {
    padding: '10px',
    '&:hover': {
    background: 'blue'
    }
    },
    '@media (min-width: 1024px)': {
    button: {
    padding: '20px'
    }
    }
    }
    

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79. Before: CSS-modules
    import styles from './Button.css'
    const Button = ({ children }) => (
    
    
    { children }
    
    
    )
    

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80. After: JSS
    import injectSheet from 'react-jss'
    import styles from './styles'
    const Button = ({ classes, children }) => (
    
    
    {children}
    
    
    )
    export default injectSheet(styles)(Button)
    

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81. CSS-in-JS (JSS)
    ✅ Explicit imports
    ✅ Scoped & fast selectors
    ✅ True rules isolation
    ✅ Code reuse, expressiveness
    ✅ Framework agnostic
    ✅ Uses w3c standard
    ✅ No build step is required
    ✅ Dead code elimination
    ✅ Automatic vendor prefixing
    

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82. —If we generate class names,
    why do we still use class attribute?
    

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83. https://www.styled-components.com/
    

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84. // Create a Title component that'll
    render an tag with some styles
    const Title = styled.h1`
    font-size: 1.5em;
    text-align: center;
    color: palevioletred;
    `;
    render(
    
    Hello React Alicante!
    
    );
    

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85. const Button = styled.button`
    /* Adapt the colors based on primary prop */
    background: ${props => props.primary ? 'palevioletred' : 'white'};
    color: ${props => props.primary ? 'white' : 'palevioletred'};
    font-size: 1em;
    margin: 1em;
    padding: 0.25em 1em;
    border: 2px solid palevioletred;
    border-radius: 3px;
    `;
    render(
    
    Normal
    Primary
    
    );
    

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86. styled-components
    ✅ No messing with classNames (implementation detail)
    ✅ Same mental model and structure for the whole
    application
    

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87. “styled-components […] removes the
    mapping between components and styles.”
    https://www.styled-components.com/
    

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88. Styled Components
    

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89. Styled Primitives
    

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90. styled-components for react-native
    import styled from 'styled-components/native';
    const StyledView = styled.View`
    background-color: papayawhip;
    `;
    const StyledText = styled.Text`
    color: palevioletred;
    `;
    class MyReactNativeComponent extends React.Component {
    render() {
    return (
    
    Hello World!
    
    )
    }
    }
    

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91. styled-components for Sketch
    

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93. Past Current time Future
    

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94. Universal
    rendering
    

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95. import React from 'react';
    import {AppRegistry, Pano, Text, View} from 'react-vr';
    class WelcomeToVR extends React.Component {
    render() {
    // Displays "hello" text on top of a loaded 360 panorama image.
    // Text is 0.8 meters in size and is centered three meters in front
    of you.
    return (
    
    
    style={{
    fontSize: 0.8,
    layoutOrigin: [0.5, 0.5],
    transform: [{translate: [0, 0, -3]}],
    }}>
    hello
    
    
    );
    }
    };
    AppRegistry.registerComponent('WelcomeToVR', () => WelcomeToVR);
    

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100. Design systems shared between
     designers and developers!
     

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102. Wait! But…
     Myths & misconceptions about CSS-in-JS
     

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103. “CSS-in-JS is slow”
     

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105. 1. CSS-in-JS ≠ inline styles!
     

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106. import { css } from 'glamor'
     const title = css({
     fontSize: '1.8em',
     fontFamily: 'Comic Sans MS',
     color: 'blue'
     })
     console.log(title)
     // → 'css-1pyvz'
     

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107. 2. CSS-in-JS is fast enough
     

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108. http://cssinjs.org/function-values/
     

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109. 3. Maintanability > Speed
     

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110. https://twitter.com/dan_abramov/status/842329893044146176
     

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112. https://codepen.io/malyw/pen/XRRgeB
     

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114. “Crafted CSS is better for performance”
     

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116. https://meiert.com/en/blog/20170531/70-percent-css-repetition/
     “In CSS, we repeat ourselves too much.
     While it’s absolutely, practically possible
     to limit declaration repetition to 10–
     20%, reality averages 72% (median
     66%).”
     

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117. Functional CSS?
     

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118. http://tachyons.io
     

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119. Tachyons
     
     
     Title
     
     
     Lorem ipsum dolor sit amet.
     
     
     

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122. Manual work
     

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124. Enables CSS optimisations
     

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125. …but uses very simple API
     import {styled} from 'styletron-react';
     const Panel = styled('div', (props) => ({
     backgroundColor: props.alert ? 'orange' : 'lightblue',
     fontSize: '12px'
     }));
     Danger!
     

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126. airbnb.com CSS output size
     

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127. Use functional CSS
     

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128. Generate functional CSS
     

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131. “It’s not real CSS!”
     

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133. SASS has variables, mixins, etc.
     

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134. JavaScript has variables, functions
     

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135. https://una.im/sass-es2015/#
     

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136. Variables
     let color = "red";
     $color: "red";
     

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137. Lists
     const colorArray = ["red", "yellow", "green"];
     for (let color of colorArray) {
     console.log(color);
     }
     $colorList: "red", "yellow", "green";
     @each $color in $colorList {
     @debug $color;
     }
     

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138. Functions
     function PrintMe(firstArg, ...theRest) {
     console.log(firstArg, theRest);
     }
     @mixin funCircle($size, $gradient ...) {
     width: $size;
     height: $size;
     background: radial-gradient($gradient);
     }
     

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139. https://polished.js.org/
     

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140. // Styles as object usage
     const styles = {
     background: lighten(0.2, '#CCCD64'),
     background: lighten(0.2, 'rgba(204,205,100,0.7)'),
     }
     // styled-components usage
     const div = styled.div`
     background: ${lighten(0.2, '#FFCD64')};
     background: ${lighten(0.2, 'rgba(204,205,100,0.7)')};
     `
     // Output
     element {
     background: "#e5e6b1";
     background: "rgba(229,230,177,0.7)";
     }
     

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141. “You should use the Platform”*
     * Or, just Google Chrome?
     

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147. styled-jsx
     export default () => (
     
     only this paragraph will be red
     {`<br/>p {<br/>color: red;<br/>}<br/>`}
     
     )
     

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148. styled-jsx
     import _JSXStyle from 'styled-jsx/style'
     export default () => (
     
     only this paragraph will get the
     style :)
     {color: red;}`} />
     
     )
     

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150. “CSS is simple”
     

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151. CSS is simple
     

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152. CSS is simple CSS is easy
     ≠
     

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153. https://adactio.com/journal/12571
     “It is simple in the sense of “not complex”,
     but that doesn’t mean it’s easy. Mistaking
     “simple” for “easy” will only lead to
     heartache.”
     

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154. How many of you know how to
     extract critical CSS or doing that?
     ✋
     

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155. Critical CSS with <>
     import { renderToString } from 'react-dom/server'
     import { ServerStyleSheet } from 'styled-components'
     const sheet = new ServerStyleSheet()
     const html = renderToString(sheet.collectStyles())
     const css = sheet.getStyleTags()
     

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156. https://medium.com/seek-blog/a-unified-styling-language-
     d0c208de2660
     “If you build your app with progressive
     enhancement in mind, despite being
     written entirely in JavaScript, it might not
     require JavaScript on the client at all.”
     

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157. Takeaways
     

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159. “CSS-in-JS enforces the best practices
     trough technology and shared knowledge.”
     

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160. It’s still CSS and you still
     have to learn it!
     

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161. It’s not about how fast you can write code,
     it’s about how fast you can read it.
     

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162. Stay open-minded &
     keep experimenting!
     

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164. Thank you!
     

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165. Andrey Okonetchnikov
     @okonetchnikov
     http://okonet.ru
     https://github.com/okonet
     UI Engineer @ Feedly
     

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