util-array-object-or-both

util-array-object-or-both

Validate and normalise user choice: array, object or both?

Table of Contents

• Table of Contents
• Install
• Purpose
• API
• Use
• Critique
• Contributing
• Licence

Install

npm i util-array-object-or-both

// consume via a CommonJS require:
const arrObjOrBoth = require("util-array-object-or-both");
// or as an ES Module:
import arrObjOrBoth from "util-array-object-or-both";

Here's what you'll get:

Type	Key in package.json	Path	Size
Main export - CommonJS version, transpiled to ES5, contains require and module.exports	main	dist/util-array-object-or-both.cjs.js	3 KB
ES module build that Webpack/Rollup understands. Untranspiled ES6 code with import/export.	module	dist/util-array-object-or-both.esm.js	2 KB
UMD build for browsers, transpiled, minified, containing iife's and has all dependencies baked-in	browser	dist/util-array-object-or-both.umd.js	17 KB

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Purpose

When I give the user ability to choose their preference out of: array, object or any, I want to:

• Allow users to input the preference in many ways: for example, for array, I also want to accept: Arrays, add, ARR, a. Similar thing goes for options object and any.
• Normalise the choice - recognise it and set it to one of the three following strings: array, object or any. This is necessary because we want set values to use in our programs. You can't have five values for array in an IF statement, for example.
• When a user sets the preference to unrecognised string, I want to throw a meaningful error message. Technically this will be achieved using an options object.
• Enforce lowercase and trim and input, to maximise the input possibilities

	Assumed to be an array-type	object-type	either type
Input string:	array	object	any
	arrays	objects	all
	arr	obj	everything
	aray	ob	both
	arr	o	either
	a		each
			whatever
			e
	----	----	----
Output string:	array	object	any

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API

API is simple - just pass your value through this library's function. If it's valid, it will be normalised to either array or object or any. If it's not valid, an error will be thrown.

Input argument	Type	Obligatory?	Description
input	String	yes	Let users choose from variations of "array", "object" or "both". See above.
opts	Plain object	no	Optional Options Object. See below for its API.

Options object lets you customise the thrown error message. It's format is the following:

${opts.msg}The ${opts.optsVarName} was customised to an unrecognised value: ${str}. Please check it against the API documentation.

options object's key	Type	Obligatory?	Default	Description
{
msg	String	no	``	Append the message in front of the thrown error.
optsVarName	String	no	given variable	The name of the variable we are checking here.
}

For example, set optsVarName to opts.only and set msg to ast-delete-key/deleteKey(): [THROW_ID_01] and the error message thrown if user misconfigures the setting will be, for example:

ast-delete-key/deleteKey(): [THROW_ID_01] The variable "opts.only" was customised to an unrecognised value: sweetcarrots. Please check it against the API documentation.

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Use

// require this library:
const arrObjOrBoth = require('util-array-object-or-both')
// and friends:
const clone = require('lodash.clonedeep')
const checkTypes = require('check-types-mini')
const objectAssign = require('object-assign')
// let's say you have a function:
function myPrecious (input, opts) {
  // now you want to check your options object, is it still valid after users have laid their sticky paws on it:
  // define defaults:
  let defaults = {
    lalala: null,
    only: 'object' // <<< this is the value we're particularly keen to validate, is it `array`|`object`|`any`
  }
  // clone the defaults to safeguard it, and then, object-assign onto defaults.
  // basically you fill missing values with default-ones
  opts = objectAssign(clone(defaults), opts)
  // now, use "check-types-mini" to validate the types:
  checkTypes(opts, defaults,
    {
      // give a meaningful message in case it throws,
      // customise the library `check-types-mini`:
      msg: 'my-library/myPrecious(): [THROW_ID_01]',
      optsVarName: 'opts',
      schema: {
        lalala: ['null', 'string'],
        only: ['null', 'string']
      }
    }
  )
  // by this point, we can guarantee that opts.only is either `null` or `string`.
  // if it's a `string`, let's validate is its values among accepted-ones:
  opts.only = arrObjOrBoth(opts.only, {
    msg: 'my-library/myPrecious(): [THROW_ID_02]',
    optsVarName: 'opts.only'
  })
  // now we can guarantee that it's either falsey (undefined or null) OR:
  //   - `object`
  //   - `array`
  //   - `any`

  // now you can use `opts.only` in your function safely.
  ...
  // rest of the function...
}

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Critique

You may ask, why on Earth you would need a package for such thing? It's not very universal to be useful for society, is it?

Actually, it is.

I discovered that when working with AST's, you often need to tell your tools to process (traverse, delete, and so on) EITHER objects OR arrays or both. That's where this library comes in: standardise the choice (from three options) and relieve the user from the need to remember the exact value.

I think the API should accept a very wide spectrum of values, so users would not even need to check the API documentation - they'd just describe what they want, in plain English.

I'm going to use it in:

• ast-monkey
• json-variables
• ast-delete-key

and others. So, it's not that niche as it might seem!

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Contributing

• If you want a new feature in this package or you would like us to change some of its functionality, raise an issue on this repo.

• If you tried to use this library but it misbehaves, or you need advice setting it up, and its readme doesn't make sense, just document it and raise an issue on this repo.

• If you would like to add or change some features, just fork it, hack away, and file a pull request. We'll do our best to merge it quickly. Prettier is enabled, so you don't need to worry about the code style.

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Licence

MIT License (MIT)

Copyright © 2018 Codsen Ltd, Roy Revelt