The short answer is it will take you between 1-12 months of learning to become proficient with React. This depends on your existing software development experience, your knowledge of javascript and the learning path you take.
Read moreIs it hard to learn React Native?
Learning mobile development is not a piece of cake and comparatively difficult than web development mostly. No matter if you choose to learn React Native (which is one of the easiest ) or any other platform/framework for mobile development.
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