@kyon45/subscriptable NPM

A decorator library makes ESNext Class subscriptable.

Installation

npm install @kyon45/subscriptable

yarn add @kyon45/subscriptable

Usage

Decorator

// esm
import subscriptable from '@kyon45/subscriptable';

@subscriptable('_data')
class MyData<T> {
  private _data: T[] = [];

  push(...values: T[]): void {
    this._data.push(...values);
  }
}

const d = new MyData<number>();
d[0]   // undefined
d.push(0, 1, 2);
d[0]   // 0
d[1]   // 1
d[2]   // 2

Trap

// esm
import { trap as subscriptable } from '@kyon45/subscriptable';
// or
import subscriptable from '@kyon45/subscriptable/lib/trap';

class MyData<T> {
  private _data: T[] = [];

  push(...values: T[]): void {
    this._data.push(...values);
  }
}

const MyDataProxied = subscriptable(MyData, '_data');

const d = new MyDataProxied<number>();
d[0]   // undefined
d.push(0, 1, 2);
d[0]   // 0
d[1]   // 1
d[2]   // 2

Something like `getitem` ?

If you do not pass a prop ('_data' in the above examples), you can choose to define an at method, somehow like __getitem__ in Python.

// esm
import subscriptable from '@kyon45/subscriptable';

@subscriptable()
class MyData {
  private _data: string;

  constructor(data: string) {
    this._data = data;
  }

  at(index: number): string {
    return this._data.substr(index, 1);
  }
}

const d = new MyData('subscriptable');
d[0]    // 's'
d[2]    // 'b'
d[-1]   // 'e'