Arity

Set a functions arity (the argument count) by proxying function calls.

P.S. If you need need to enforce arity and don't care about argument length or this, use nary. It's magnitudes faster than using .apply to proxy arguments.

When would I use this?

It's unlikely you'll need to use this utility in everyday development. The reason I wrote it was for functional utilities and backward compatibility with user expectations. For example, many modules use function arity to decide how the function behaves (e.g. error middleware in express, callbacks in mocha).

Installation

npm install util-arity --save

Usage

var fn = function () {};
var arity = require('util-arity');
 
var oneArg = arity(1, fn);
var twoArgs = arity(2, fn);
var threeArgs = arity(3, fn);
 
oneArgs.length; //=> 1
twoArgs.length; //=> 2
threeArgs.length; //=> 3

TypeScript

The typings for this project are available for node module resolution with TypeScript.

License

MIT