#12 Preparing for React: The Biggest Downside of .then() Chains and Why Your Code Is Going to Hel...
Think .then().then() chains have solved Callback Hell forever? Not really. In this lesson, we'll explore the main architectural flaw of pure Promises: scope isolation. You'll see how attempting to pass data from step one to step four breaks code and forces developers to build unreadable "staircases" all over again.
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💡 Cheat sheet for the lesson:
Each callback inside a .then() method is an isolated function with its own local scope. Variables created inside the first .then() (for example, a list of users retrieved from the server) are, by default, not accessible in subsequent methods in the chain. If we need data from different steps simultaneously, pure chaining forces us to either create a multitude of global variables or fall back into nesting.
#javascript #react #promises #frontend #devhotspot