I have coded a function, that has 3 arguments, one of them is a callback function. How do I make the callback an optional argument without having to code another function without the callback argument?

If you want more control over invoking it, use call , apply , bind whatever achieves your goal. By posting your answer, you agree to the privacy policy and terms of service. Stack Overflow Questions Developer Jobs Documentation beta Tags Users.

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Optional callback in javascript (Example)

Join the Stack Overflow Community. Stack Overflow is a community of 7. Join them; it only takes a minute: Simple, just check if callback is defined before you call it.

How to use optional arguments in functions (with optional callback)

Lucas Green 3, 13 Ensure the callback is a function, and then invoke it. Much prefer the style of Mythril's answer.

No, I just don't like the way you've written it on a single line. As a user of someone else's interface, I would want to know if the value I inserted was not the expected value, rather that just having it ignored.

I would still expect say 'hello', 'world' to error out. Otherwise I'll never know that isn't what the function expects. Hopefully people aren't fishing around with different arguments to infer a function's argument signature though: Sign up or log in StackExchange.

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Do's and Don'ts · TypeScript

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