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Radoslav Stankov 23/11/2019 Eliminating noise from your code

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Radoslav Stankov @rstankov blog.rstankov.com github.com/rstankov
 twitter.com/rstankov

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https://speakerdeck.com/rstankov

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Huey

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Huey Dewey

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Huey Dewey Louie

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Why code gets bad overtime? !

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What is a good code? "

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#

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Is this good code? $

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Why not? %

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... too much information density

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... too much information noise &

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“In cognitive psychology, cognitive load refers to the used amount of working memory resources. ” - WikipediA Cognitive load

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“Ego depletion refers to the idea that self- control or willpower draws upon a limited pool of mental resources that can be used up.” - WikipediA Ego depletion

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$(document).on('click', '[data-accordion="item"]', function() {
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“It is better to be a good programmer with great habits, than a great programmer.” - Kent Beck

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Broken windows theory

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“Social psychologists and police officers tend to agree that if a window in a building is broken and is left unrepaired, all the rest of the windows will soon be broken.” - WikipediA Broken windows theory

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The Boy Scout Rule

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“Leave your code better than you found it.” The Boy Scout Rule

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Radoslav Stankov 05/05/2018 Eliminating noise from your code

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Radoslav Stankov 05/05/2018 Eliminating ' Code Smells '

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Code smell is any symptom in the source code of a program that possibly indicates a deeper problem. Code smells

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Code smells are usually not bugs—they are not technically incorrect and don't currently prevent the program from functioning. Instead, they indicate weaknesses in design that may be slowing down development or increasing the risk of bugs or failures in the future. Code smells

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Code refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior Refactoring

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Refactoring

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#1 Useless Code

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function LoadMoreBaseOnDevice(props) { return ( <> > ); }

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function LoadMoreBaseOnDevice(props) { return ( {isMobile => isMobile ? ( ) : ( ) } ); }

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function LoadMoreBaseOnDevice(props) { const isMobile = useIsMobile(); return isMobile ? ( ) : ( ); }

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click(event)} />

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click(event)} />

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function Component({ array }) { return ( {array && array.length > 0 && array.map(item => )} ); }

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function Component({ array }) { return ( {array && array.length > 0 && array.map(item => )} ); }

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function Component({ array }) { return ( {array && array.map(item => )} ); }

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function Component({ array }) { return ( {array.map(item => )} ); }

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function Component({ array }) { return ( {array.map(item => )} ); }

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function Component({ array }) { return array.map(item => ); }

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{(variant, complete) => { return variant == 'left' ? ( viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) ) : viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ); }}

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{(variant, complete) => { return variant == 'left' ? ( viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) ) : viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ); }}

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{(variant, complete) => variant == 'left' ? ( viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) ) : viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) } ;

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#2 Too Much Conditional Logic

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{(variant, complete) => variant == 'left' ? ( viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) ) : viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) } ;

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{(variant, complete) => variant == 'left' ? ( viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) ) : viewer ? ( !viewer.isSubscribedToNewsletter && ( ) ) : ( ) } ;

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{(variant, complete) => variant == 'left' ? ( ) : ( ) }

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{(variant, complete) => variant == 'left' ? ( ) : ( ) }

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{(variant, complete) => ( )}

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function Card({ card }) { if (card.type === 'news') { return ; } if (card.type === 'post') { return ; } if (card.type === 'user') { return ; } return ; }

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const CARDS = { news: NewsCard, post: PostCard, user: UserCard, }; function Card({ card }) { const Component = CARDS[card.type] || DefaultCard; return ; }

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function ShareButton({ sharable, medium }) { const icon = medium === 'twitter' ? : ; const onClick = () => { if (medium === 'facebook') { shareOnFacebook(sharable); } else { shareOnTwitter(sharable); } }; return ( ); }

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function ShareButton({ sharable, medium }) { const icon = medium === 'twitter' ? : ; const onClick = () => { if (medium === 'facebook') { shareOnFacebook(sharable); } else { shareOnTwitter(sharable); } }; return ( ); }

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const MEDIUMS = { twitter: { icon: , title: 'Share on Twitter', share: shareOnTwitter, }, facebook: { icon: , title: 'Share on Facebook', share: shareOnFacebook, }, }; function ShareButton({ sharable, medium }) { const medium = MEDIUMS[medium]; return ( medium.share(sharable)} /> ); }

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const MEDIUMS = { twitter: { icon: , title: 'Share on Twitter', share: shareOnTwitter, }, facebook: { icon: , title: 'Share on Facebook', share: shareOnFacebook, }, linkedin: { icon: , title: 'Share on LinkedIn', share: shareOnLinkedIn, }, }; function ShareButton({ sharable, medium }) { const medium = MEDIUMS[medium]; return ( medium.share(sharable)} />

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interface IProps { sharable: ISharable; medium: keyof typeof MEDIUMS; }

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http://blog.rstankov.com/replace-conditional-with-map-refactoring/

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#3 Too DRY code

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Good DRY

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The bad side of DRY

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const API_GET = '/api/:source_type/:id'; const API_GET_DETAILS = '/api/:source_type/:id/details'; const API_GET_VERSION = '/api/:source_type/:id/on/:year/:date/:month'; const API_GET_SUBTYPE = '/api/:source_type/:id/sub/:subtype/:subtype_id';

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const API = 'api'; const SOURCE_ID = '/:id'; const SOURCE_DATE = '/:year/:month/:day'; const SUBTYPE = '/:subtype'; const SUBID = '/:subtype_id'; const API_GET = API + SOURCE_TYPE + SOURCE_ID; const API_GET_DETAILS = API + SOURCE_TYPE + SOURCE_ID + '/details'; const API_GET_VERSION = API + SOURCE_TYPE + SOURCE_ID + '/on' + SOURCE_DATE; const API_GET_SUBTYPE = API + SOURCE_TYPE + SOURCE_ID + '/sub' + SUBTYPE + SUBID;

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function path(rest = '') { return `${BASE_PATH}${rest}`; } function token(string) { return `${SEPARATOR}${string}`; } const SEPARATOR = '/'; const API = 'api'; const SOURCE_TYPE = ':source_type'; const SOURCE_ID = ':id'; const YEAR = ':year'; const MONTH = ':month'; const DAY = ':day'; const SUBTYPE = ':subtype'; const SUBID = ':subtype_id'; const DETAILS = 'details'; const ON = 'on'; const SUB = 'sub'; const BASE_PATH = token(API) + token(SOURCE_TYPE) + token(SOURCE_ID); const DATE_PART = token(YEAR) + token(MONTH) + token(DAY); const SUB_PART = token(SUBTYPE) + token(SUBID); const API_GET = path(); const API_GET_DETAILS = path(token(DETAILS)); const API_GET_VERSION = path(token(ON) + token(DATE_PART)); const API_GET_SUBTYPE = path(token(SUB) + token(SUB_PART));

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Don't repeat yourself (DRY) is a principle of software development aimed at reducing repetition of software patterns, replacing it with abstractions or using data normalization to avoid redundancy. Don't repeat yourself

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The DRY principle is stated as "Every piece of knowledge must have a single, unambiguous, authoritative representation within a system" Don't repeat yourself

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#4 Single Level of Abstraction

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SLAP Single Level of Abstraction Principle SLAP

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function Cart() { const [cart, setData] = useState(selectData(DataSource)); const callback = useCallback(selectData, []); useEffect(() => { const removeChangeListener = DataSource.addChangeListener(() => setData(callback(DataSource)), ); return removeChangeListener; }, [callback]); return (

Cart ({cart.length})

    {cart.map(item => (
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); }

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function Cart() { const [cart, setData] = useState(selectData(DataSource)); const callback = useCallback(selectData, []); useEffect(() => { const removeChangeListener = DataSource.addChangeListener(() => setData(callback(DataSource)), ); return removeChangeListener; }, [callback]); return (

Cart ({cart.length})

    {cart.map(item => (
    • ))}
); }

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function Cart() { const [cart, setData] = useState(selectData(DataSource)); const callback = useCallback(selectData, []); useEffect(() => { const removeChangeListener = DataSource.addChangeListener(() => setData(callback(DataSource)), ); return removeChangeListener; }, [callback]); return (

Cart ({cart.length})

    {cart.map(item => (
    • ))}
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function Cart() { const cart = useData(getCartData); return (

Cart ({cart.length})

    {cart.map(item => (
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function useData(selectData: (data: DataSourceClass) => T): T { const [data, setData] = useState(selectData(DataSource)); const callback = useCallback(selectData, []); useEffect(() => { const removeChangeListener = DataSource.addChangeListener(() => setData(callback(DataSource)), ); return removeChangeListener; }, [callback]); return data; }

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( Duplicated Code ) Long Method * Large Class + Long Parameter List , Shotgun Surgery - Feature Envy . Data Clumps / Case Statements 0 Parallel Inheritance Hierarchies 1 Speculative Generality 2 Temporary Field 3 Message Chains 4 Middle Man 5 Alternative Classes with Different Interfaces 6 Refused Bequest 7 Comments 8 Repetitive Boilerplate 9 God object ' : and more ...

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Thanks ;

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https://speakerdeck.com/rstankov

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