@kingjs/property-descriptor.initialize.extension v1.0.1

@kingjs/property-descriptor.initialize.extension

Lazily declare an accessor or function but only for specific polymorphic types.

Usage

var assert = require('assert')
var initializeExtension = require('@kingjs/property-descriptor.initialize.extension');

function capitalize() {
  var firstChar = this.charAt(0);

  // capitalize
  firstChar = firstChar.toUpperCase();
  
  var result = firstChar + this.substring(1, this.length);
  return result;
}

var Capitalize = Symbol(capitalize.name);

Object.defineProperty(
  Object.prototype,
  Capitalize,
  initializeExtension.call(
    { value: capitalize },
    Capitalize,
    () => String
  )
);

var test = 'foobar'[Capitalize]();
assert(test == 'Foobar');

var descriptor = Object.getOwnPropertyDescriptor(String.prototype, Capitalize);
assert(descriptor.value == capitalize);

assert.throws(() => [][Capitalize]());

API

extension(this, name, callback())

Parameters

• this: A descriptor describing an accessor or function.
• name: The symbol of the property being described.
• callback: Returns a type this must be polymorphic with before patching the definition.

Returns

A descriptor whose accessors or function has been replaced with a stub which checks that this is polymorphic with the extended type before patching and invoking the accessor or function.

Install

With npm installed, run

$ npm install @kingjs/property-descriptor.initialize.extension

Source

https://repository.kingjs.net/property-descriptor/initialize/extension

License

MIT