extension-methods-js

extension-methods-js

This package is inspired by C#'s extension methods. This package provides a function that will bind an extension type to whatever target type you want those methods to be on.

Table of Contents

1. Installation
2. Basic Usage

Installation:

npm i extension-methods-js

Basic Usage:

import { bindExtensions } from 'extension-methods-js';

// For TypeScript, update the target type interfaces with extension methods.
// Be sure to OMIT the first argument (the target) and that methods are NOT static.
declare global {
  interface Array<T> {
    clear(): void;
  }

  interface Set<T> {
    pipe(action: (item: T) => void): void;
  }
}
 
// Define extension classes.
// Ensure each method is static and the first argument is the target type.
class ArrayExtensions {
  public static clear<TSource>(arr: TSource[]): void {
    arr.length = 0;
  }
}

class SetExtensions {
  public static pipe<TSource>(set: TSource[], action: (item: TSource) => void): void {
    for (const item of set) {
      action(item);
    }
  }
}

// Bind extension classes to targets.
bindExtensions([[ArrayExtensions, Array], [SetExtensions, Set]]);
// You can also use the other overload bindExtensions(ArrayExtensions, Array) if you only have one extension class.

const arr = [1, 2, 3];

// Arrays now have extension methods.
arr.clear();

// Will be []
console.log(arr);

const set = new Set([1, 2, 3]);

// Sets now have extension methods.
set.pipe(x => console.log(x));