Return Types of Callbacks
Don’t use the return type any for callbacks whose value will be ignored:
1 2 3 4 | /* WRONG */function fn(x: () => any) { x();} |
Do use the return type void for callbacks whose value will be ignored:
1 2 3 4 | /* OK */function fn(x: () => void) { x();} |
Why: Using void is safer because it prevents you from accidently using the return value of x in an unchecked way:
1 2 3 4 | function fn(x: () => void) { var k = x(); // oops! meant to do something else k.doSomething(); // error, but would be OK if the return type had been 'any'} |
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