How do I practice reading class components?
Find an older open-source React project, made before 2020, and read its class components. Practice understanding the state flow and lifecycle without writing anything. This builds the reading fluency you need for legacy codebases.
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More FAQs in A Focused Roadmap for Understanding React Class Components
Just enough to read legacy code and pass interviews. Learn the syntax, this.state and this.setState, the three main lifecycle methods, the mapping to hooks, the this problem, and error boundaries. You do not need to master writing them.
The lifecycle methods. Knowing when componentDidMount, componentDidUpdate, and componentWillUnmount run, and how they map to useEffect, is the most commonly tested part of class components in interviews.
Because it reinforces your understanding of hooks and lets you convert class code to functional code. The mapping, componentDidMount to useEffect and so on, is also a common interview question.
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