sindresorhus / arrify

Convert a value to an array

arrify

Convert a value to an array

If you simply want to accept both a single value and multiple values, you can use [singleValueOrArray].flat() instead.

Install

npm install arrify

Usage

import arrify from 'arrify';

arrify('🦄');
//=> ['🦄']

arrify(['🦄']);
//=> ['🦄']

arrify(new Set(['🦄']));
//=> ['🦄']

arrify(null);
//=> []

arrify(undefined);
//=> []

Specifying null or undefined results in an empty array.

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arrify's Issues

Invalid @@iterator method will produce an error

If an iterable's @@iterator method does not return an iterator object, then it is a non-well-formed iterable.
Just like this:

import arrify from "arrify";

let iterable = {  
  0: "a",  
  1: "b",  
  2: "c",  
  length: 3,  
  [Symbol.iterator]: () => 1,  
};  
console.log(arrify(iterable));

You will get an error:

file:///D:/05-personal/node/nodejs-debugging/node_modules/arrify/index.js:15
                return [...value];
                           ^

TypeError: Result of the Symbol.iterator method is not an object
    at arrify (file:///D:/05-personal/node/nodejs-debugging/node_modules/arrify/index.js:15:14)
    at file:///D:/05-personal/node/nodejs-debugging/src/index.js:50:13
    at ModuleJob.run (node:internal/modules/esm/module_job:185:25)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:281:24)
    at async loadESM (node:internal/process/esm_loader:88:5)
    at async handleMainPromise (node:internal/modules/run_main:65:12)
error Command failed with exit code 1.

Doesn't work with array-like objects

This sounded interesting but my main use case would be transforming results from document.querySelector(All) to arrays, and that doesn't work (meaning that they end up in a single-element array, always)

Can this be modified to work with array-like objects?

Unable to use import syntax in TypeScript

I am unable to import this package through TypeScript.
When I try, it gives me the following error

Module '"path/to/project/node_modules/arrify/index"' can only be default-imported using the 'esModuleInterop' flagts(1259)
index.d.ts(38, 1): This module is declared with using 'export =', and can only be used with a default import when using the 'esModuleInterop' flag.

type definitions don't work for tuple types

declare let tuple: [number, string];

const arrified = arrify(tuple);
arrified.push(1);
arrified[0] = 'foo'

Since tuples are arrays, they are returned as is. The type declarations however widen the type to a regular (mutable) array type. Both mutations above should not be allowed.

type definitions don't work for union types

arrify(Boolean() ? [1, 2] : 3);

The above returns the type (number | number[])[]. This doesn't match the runtime value of number[]

Support for multiple arguments

Would it make sense to include support for multiple arguments?

var arrify = require('arrify');
arrify('unicorn', 'unicorn');

and if so, would it then best return:

//=> ['unicorn', 'unicorn']

or

//=> [['unicorn'], ['unicorn']]

or is the module intentionally strict to only support one argument?

Thanks!