TechTalk - 2o22 - JS/ TS/ React mistakes and how to avoid them

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JS/ TS/ React mistakes and how to avoid them

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HypeTech Tech education and shaping ideas into hype products hypetech.io | reactweek.dev Marko Arsić Founder and CEO @ HypeTech Founder of HypeTech Education Lecturer @ ReactWeek.dev Independent Tech Consultant Helping companies set up teams and standardize the development process github.com/marsicdev

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Each developer has to overcome troubles and obstacles That’s the job!

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There are no exceptions here and each ﬁeld is diﬃcult and it seems rather hard to avoid mistakes at the very start.

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General mistakes 🤕

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We all fail to do this Planning Architecturing Documenting Testing Decoupling Automating

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Not always, but more than often. It’s a fact !

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JavaScript mistakes

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Not understanding all ES features === vs == !! Optinals

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Not understanding pure functions filter, map, reduce

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Not using virtual properties in classes and private ﬁelds

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Promise (chain, return types)

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Some compare async/await with Promise and claim it is the next generation in the evolution of JavaScript asynchronous programming

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async/await IS an improvement, but it is no more than a syntactic sugar, which will not change our programming style completely.

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Async functions are still promises. You have to understand promises before you can use async functions correctly, most of the time you need to use promises along with async functions.

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TypeScript mistakes

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Not Enabling Strict Mode Without TypeScript strict mode on, the typing can be too lax, and that will make our codebase less type-safe. It will give the wrong impression, as some think that by adding TypeScript all typing issues are automatically ﬁxed.

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Redeclaring interfaces When typing component interfaces, it is common to need to have some different interfaces variants of the same type. Those can vary in one or two parameters. A common mistake is to manually redeﬁne those variations. That will lead to: ● unnecessary boilerplate. ● multiple changes are needed if one property changes in one place, that change needs to be propagated to many ﬁles.

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Not Relying on Type Inference TypeScript inference is one of the most powerful tools of this programming language. It does all the work for us. We only have to make sure that all the pieces add together with as little intervention as possible. A crucial operator to achieving this is the typeof.

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Incorrect use of Overloading TypeScript supports overloading natively. That is great as it can improve the readability of our contracts. However, it is different from other typed overloading languages. There are scenarios where it might make our code more complex and verbose.

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Using the Function Type TypeScript ships with the Function type. It is like using the any keyword but for functions only. Enabling strict mode won’t prevent us from using it. Function type: ● accepts any number and type of parameters. ● the return type is always any

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Relying on a Third Party for Immutability TS provides all the necessary tooling to make sure we don’t mutate our objects. We don’t need to add heavy libraries like ImmutableJS to our codebase.

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React mistakes

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Decomposition / Decoupling

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Decomposition / Decoupling

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Modifying state directly

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Setting new state that relies on the previous state without using a function

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Forgetting that setState is asynchronous

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Writing logic in components

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Updatating state on unmounted component

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Not creating enough components Creating to many components

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Not handling errors

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Not using prop-types when writing JavaScript

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Not using absolute paths

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Not using key on a listing component

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Not using helper models, classes, functions or custom hooks (react-use)

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Using X for absolutely everything / Using X unnecessarily

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Not using Developer Tools

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Summary

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These guidelines are simple to follow and are meant to help you embrace ecosystem rather than ﬁght it.

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By applying these simple tips you will have a better, less verbose, and easy to maintain codebase.

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Q & A As everything good in life, knowledge is great only when shared https://discord.gg/94uhCAkFKf

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As everything good in life, knowledge is great only when shared hypetech.io/education

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[email protected]