Why are first-class functions important in JavaScript?
They enable callbacks, higher-order functions (map, filter, reduce), functional programming (composition, pure functions), and event handling. Almost all async patterns in JS rely on functions being first-class.
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More FAQs in Functions as First-Class Citizens in JavaScript
Functions are treated like any other value. They can be assigned to variables, passed as arguments, returned from other functions, stored in data structures, and have a type (typeof is 'function').
Yes. Passing functions as arguments is how callbacks work. setTimeout, map, filter, fetch.then, and event listeners all accept functions as arguments.
Yes. A function that returns another function is called a higher-order function. The returned function often captures the outer variable environment, creating a closure.
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