November 6, 2023
What is a function signature?
At its simplest, a function signature includes the function name and parameter list. Here's an example of a basic function with its signature:
In this case,
greet is the function name, and
name is a single parameter.
Parameters in function signatures
sum takes two parameters:
say is called without arguments, it uses the default value of
A rest parameter allows a function to accept an indefinite number of arguments as an array:
Destructuring can also be used in function parameters to directly extract values from objects or arrays:
Functions that take other functions as parameters or return functions are known as higher-order functions. Their signatures can become complex:
Function signature with TypeScript
In TypeScript, both parameter types and the return type are part of the signature.
Overloading function signatures
Using JSDoc for type information
Arrow function signatures
Arrow functions, introduced in ES6, also have signatures, although the syntax is more concise:
multiply is a constant that holds a function taking two parameters,
Callbacks and function signatures
Callback functions are passed as arguments to other functions. Their signatures must match the expectation of the higher-order function:
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