Types of Function Headers
Explore different types of function headers in TypeScript to handle parameters effectively. Learn how to use optional callback functions, rest operators for infinite arguments, and how callback return types behave to write flexible and clean functions.
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Function with parameters
A function’s signature can have a parameter that is a function too. These function’s parameters can have parameters at their turn but don’t require the invoker to use the parameters. A standard scenario is for an optional callback function.
For example, say you have a function that lets you specify an optional error callback named error of type Error. Not using the argument occurs when notification by the callback is important, but not the details from the argument. The reason is that behind it, JavaScript provides the value. The inspection of the arguments object, when not using the argument, corroborates this assertion. However, ...