In what scenarios are closures generally used?

Closures have many practical application scenarios in programming, including "encapsulation", "functional programming", "timer and event handling", "module mode", "callback function", "loop 7 scenarios including "asynchronous operation" and "caching": 1. Encapsulation, closures can be used to create private variables and functions to achieve information hiding and encapsulation; 2. Functional programming, you can create high-order functions and delayed execution functions , currying and other functions; 3. Timer and event processing can help save local state so that the required logic can be executed at a later point in time, etc.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Closures have many practical applications in programming, some of which include:

1. Encapsulation: Closures can be used to create private variables and functions, thereby enabling information hiding and encapsulation. This is particularly useful in JavaScript, which itself does not provide a syntax similar to Java or C's private members.

2. Functional programming: In functional programming, closures are very useful tools. By using closures, you can create higher-order functions, delayed execution of functions, currying, and more.

3. Timer and event handling: When handling timers and events, closures can help save local state so that the required logic can be executed at a later point in time.

4. Module mode: Closures can be used to create modules, encapsulating related functions and data together, providing a more modular programming approach.

5. Callback function: In asynchronous programming, closures are often used with callback functions to capture the state of the surrounding scope and use these states when the callback is triggered.

6. Asynchronous operations in loops: When performing asynchronous operations in loops, using closures can solve problems caused by variable promotion in JavaScript and ensure that they can be obtained when the asynchronous operation is completed. Correct loop variable values.

7. Caching: Use closures to cache calculation results to avoid repeated calculations and improve program performance.

In short, closures are widely used in JavaScript and other languages ​​that support functional programming, and can help developers write more modular, flexible and efficient code.

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