Arrayify

This JavaScript package exports an arrayify operator that accepts various types and coerces them into arrays.

• Falsy values are coerced to an empty array.
• Delegates to the toArray method of collections that implement that method.
• Delegates to the forEach method of other collections that implement that method.
• Objects that have a length and numbered properties are coerced into an array. Note that passing arguments as an argument to arrayify will probably deoptimize the calling function. However, arrayify defends itself from being deoptimized in this fashion by iterating the given object itself.
• Throws an exception for all other cases.

Examples

Install

npm install --save pop-arrayify

Import the pop-arrayify module.

"use strict";
var arrayify = require("pop-arrayify");

Copies arrays.

var array = [1, 2, 3];
var arrayed = arrayify(array);
expect(arrayed).not.toBe(array);
expect(arrayed).toEqual(array);

Copies objects that implement toArray.

var List = require("collections/list");
var list = new List([1, 2, 3]);
expect(arrayify(list)).toEqual([1, 2, 3]);

Copies objects that implement (synchronous) forEach.

expect(arrayify({
    forEach: function (callback, thisp) {
        callback.call(thisp, 1);
        callback.call(thisp, 2);
        callback.call(thisp, 3);
    }
})).toEqual([1, 2, 3]);

Coerces array-like objects:

expect(arrayify({
    length: 3,
    0: 1,
    1: 2,
    2: 3
})).toEqual([1, 2, 3]);

Coerces falsy values to empty arrays.

expect(arrayify(null)).toEqual([]);

Supports no other cases.

expect(function () {
    arrayify({});
}).toThrow();

Polymorphic operator

A well-planned system of objects is beautiful: a system where every meaningful method for an object has been anticipated in the design. Inevitably, another layer of architecture introduces a new concept and with it the temptation to monkey-patch, dunk-punch, or otherwise cover-up the omission. But reaching backward in time, up through the layers of architecture doesn't always compose well, when different levels introduce concepts of the same name but distinct behavior.

A polymorphic operator is a function that accepts as its first argument an object and varies its behavior depending on its type. Such an operator has the benefit of covering for the types from higher layers of architecture, but defers to the eponymous method name of types yet to be defined.

Copyright and License

Copyright (c) 2015 Kristopher Michael Kowal and contributors. All rights reserved. MIT License.