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Q: can then, catch and finally sequences be reversed?

A: yes, the effect is exactly the same. However, this is not recommended, and it is best to write programs in the order of then-catch-finally.

Q: apart from then blocks, can the other two blocks be used multiple times?

A: yes, finally executes sequentially like then, but the catch block only executes the first, unless there is an exception in the catch block. So it's best to arrange only one catch and finally block.

Q: how does the then block break?

A: then blocks are executed sequentially downwards by default, and return cannot be interrupted. You can jump to catch through throw to achieve interruption.

Q: when is it appropriate to use Promise instead of traditional callback functions?

A: it is suitable for Promise when you need to perform multiple asynchronous operations sequentially, for example, if you want to detect the user name and password successively through the asynchronous method, you need to detect the user name first and then the password asynchronously.

Q: is Promise a way to convert async to synchronization?

A: not at all. Promise is just a better programming style.

Q: when do we need to write another then instead of programming in the current then?

A: when you need to call another asynchronous task.

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