@babel/helper-get-function-arity

What is @babel/helper-get-function-arity?

The @babel/helper-get-function-arity package is a utility within the Babel compiler ecosystem. It is designed to help retrieve the arity (the number of arguments) of a function. This can be particularly useful when working with transformations and manipulations of JavaScript code, where understanding the function signature is necessary for generating or modifying code accurately.

What are @babel/helper-get-function-arity's main functionalities?

Get function arity

This feature allows developers to easily determine the number of parameters that a function expects. It is particularly useful in scenarios where code is being dynamically generated or modified, and the arity of functions needs to be preserved or analyzed.

const getFunctionArity = require('@babel/helper-get-function-arity');

function myFunction(a, b, c) {}

const arity = getFunctionArity(myFunction);
console.log(arity); // Outputs: 3

Other packages similar to @babel/helper-get-function-arity

arity-n

The 'arity-n' package allows users to create a function with a specified arity. While it serves a somewhat inverse purpose compared to @babel/helper-get-function-arity, it is related in the sense that both deal with the concept of function arity. 'arity-n' can be used to enforce a specific arity on functions, which could complement the arity analysis provided by @babel/helper-get-function-arity in certain code transformation scenarios.

README

@babel/helper-get-function-arity

Function that returns the number of arguments that a function takes.

• Examples of what is considered an argument can be found at MDN Web Docs

Usage

import getFunctionArity from "@babel/helper-get-function-arity";

function wrap(state, method, id, scope) {
  // ...
  if (!t.isFunction(method)) {
    return false;
  }

  const argumentsLength = getFunctionArity(method);

  // ...
}