mimic-fn

What is mimic-fn?

The mimic-fn package is a utility that allows you to copy the properties of a function onto another function. This includes the function's name, length (the number of arguments it expects), and custom properties. It is useful when you want to wrap a function without losing its original properties, which can be important for debugging, introspection, and certain function-based APIs that rely on these properties.

What are mimic-fn's main functionalities?

Copying function properties

This feature allows you to copy all properties from the original function to the wrapper function, including the function name and custom properties.

const mimicFn = require('mimic-fn');

function original() {}
original.customProp = 'hello';

function wrapper() {
  return original();
}

console.log(wrapper.name); // 'wrapper'
console.log(wrapper.customProp); // undefined

mimicFn(wrapper, original);

console.log(wrapper.name); // 'original'
console.log(wrapper.customProp); // 'hello'

Other packages similar to mimic-fn

rename-function

The rename-function package allows you to change the name of a function, which is one aspect of what mimic-fn does. However, it does not handle copying other properties or the function's length.

README

mimic-fn

Make a function mimic another one

Useful when you wrap a function in another function and like to preserve the original name and other properties.

Install

$ npm install --save mimic-fn

Usage

const mimicFn = require('mimic-fn');

function foo() {}
foo.unicorn = '🦄';

function wrapper() {
	return foo() {};
}

console.log(wrapper.name);
//=> 'wrapper'

mimicFn(wrapper, foo);

console.log(wrapper.name);
//=> 'foo'

console.log(wrapper.unicorn);
//=> '🦄'

API

It will copy over the properties name, length, displayName, and any custom properties you may have set.

mimicFn(to, from)

to

Type: Function

Mimicking function.

from

Type: Function

Function to mimic.

Related

• rename-fn - Rename a function

License

MIT © Sindre Sorhus