typeof-items

v1.0.1

Published

3 years ago

Validate the type of array's items.

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devrafalko

type array item typeof items validation validate value loop undefined instanceof

Description

typeof-items validates the array's items' type.

Also see of-type package to check if the given value|object is of expected type
Also see typeof-arguments to validate the arguments' types passed through the enclosing function
Also see typeof-properties to validate the object's properties' types

Implementation

with NodeJS

npm install typeof-items

const type = require('typeof-items');

with Browser

Add `typeof-items.js` library to the HTML file.

The library is located in ./dist/typeof-items.js directory.
It is a webpack&babel bundled cross-browser library version.
The library is accessible as typeofItems variable in the global (window) scope.

<head>
  <script src='typeof-items.js'></script>
  <script>
    var inventors = ['Nikola', 'Albert', 'Thomas']
    typeofItems(inventors, String);
  </script>
</head>

Tests

> git clone https://github.com/devrafalko/typeof-items.git
> cd typeof-items
> npm install
> npm test        //run tests in node
> npm test deep   //run tests in node with errors shown

Usage

`type(actual, expected[, callback])`

`actual` [Array]

It should indicate the [Array] object
The item of actual array will be validated

`expected`

The expected should indicate the expected type that all items of actual array should be of

The `expected` Types

There are four ways to check the type of items:

by string expression values
by regular expression values
by constructor functions, null or undefined values
by some of supported custom types

Mind, that the typeof-items library uses the of-type library as the dependency, to validate the types. If you feel confused how to use the types, see more samples here.

[String]

Possible values:
- 'null', 'undefined'
- any value that equals to property's constructor.name, eg:
  'string', 'number', 'regexp', 'array', 'object', 'boolean','buffer', etc.
The [String] type is case insensitive:
- 'String', 'string', 'StRiNg' checks if the property is of [String] type
- 'RegExp', 'REGEXP', 'regexp' checks if the property is of [RegExp] type
The [String] type can contain multiple types, separated with |:
- 'array|object' checks if the property is of [Array] OR [Object] type
- 'undefined|null' checks if the property is of undefined OR null type

type(['Nikola', 'Albert', 'Thomas'], 'String|Number|null');

[RegExp]

Possible values:
- /null/, /undefined/
- any value matching the property's constructor.name, eg: /String/, /Number/, /RegExp/, /Array/, /Object/, /Boolean/,/Buffer/, /Promise/, etc.
Use all regular expression's features to match the type in a desired way:
- /Str/, /Err/, /Reg/, /B/
- /.+Error$/, /^RegExp$/,
- /^[A-Z][a-z]+$/
For the case insensitivity use i flag:
- /string/i, /regexp/i, /TYPEERROR/i
For multiple values use regexp (x|y) expression:
- /String|Number/, /TypeError|Error/, /(obj|str)/i

type(['Nikola', 'Albert', 'Thomas'], /number|string|undefined/i);

[Function|Array|null|undefined]

Possible values:
- null, undefined
- any [Function] constructor, eg: String, TypeError, Promise, Array, etc.
For multiple values use array:
- [String, Object, Array, null]
- [null, undefined, Boolean]

type(['Nikola', 'Albert', 'Thomas'], [Number, String, undefined]);

When you use bundlers or minifiers, use [String|RegExp] type wisely as bundlers may change the names of functions|constructors|classes in the output file.

Extra types:

[String] 'arguments' | [RegExp] /arguments/

The type 'arguments' or /arguments/ expects the item to be the function's arguments object

[String] 'instance' | [RegExp] /instance/

The type 'instance' or /instance/ expects the item to be the instance of the user's class|constructor
It fails when the item is an instance of built-in (native) constructor
- [], 'hello world', {}
It fails for instances that are the global|window's properties

[String] 'objectable' | [RegExp] /objectable/

The type 'objectable' or /objectable/ expects the item to be the object that is the instance of the Object constructor
- {}, [], new String('hello world'), new Boolean(1)
It fails when the item is a primitive value or a simple value
- 'hello world', true, 10, null, undefined

[String] 'truthy' | [RegExp] /truthy/

The type 'truthy' or /truthy/ expects the item to be like:
- 'abc', true, 1, -1, {}, [], function(){}

[String] 'falsy' | [RegExp] /falsy/

The type 'falsy' or /falsy/ expects the item to be like:
- '', false, 0, null, undefined, NaN

[String] 'any' | [RegExp] /any/ | [Array] [] | [String] ""

The type 'any' or /any/ or empty array [] or empty string "" expects the item to be of any type

`callback` [Function] (optional)

if not passed, the TypeError with default message will be thrown to the console, if any item's type is invalid.
The TypeError default message is eg.:
- Invalid [0] item. The [undefined] value has been assigned, while the value of type matching string expression "string|null" is expected.
- Invalid [1] item. The [undefined] <<falsy>> value has been assigned, while the value of type matching string expression "truthy|null" is expected.
- Invalid [5] item. The [undefined] value has been assigned, while the value of type matching regular expression /String|null/ is expected.
- Invalid [3] item. The [undefined] value has been assigned, while the value of type [String|null] is expected.
if passed, the default TypeError will not be thrown to the console and the user can decide what to do inside the callback function.
Use callback function if you don't want to stop your code execution by default (no callback) throw statement!
the callback function is executed only if at least one item value is of invalid type.
The one [Object] argument is passed through callback function with the following properties:
- index
  indicates the [Number] index of the incorrect item of the array, eg. 0, 5
- actual
  indicates the [String] actual type of the incorrect items's value, eg. "Boolean", "null"
- expected
  indicates the type(s) expected by the user, eg. "Array", "Boolean|Number", "/array|object/i"
- message
  is the default error [String] message, that you can use eg. to log in the console
- textActual
  indicates the [String] textual actual type, eg. "[undefined] <<falsy>> value"
- textExpected
  indicates the [String] textual expected type, eg. "value of type matching regular expression /String|null/"

const type = require('typeof-items');

const inventors = ['Nikola', 'Albert', 'Thomas'];

type(inventors, [Object, null], ({ message, index, expected, actual })=>{
  console.error(message);
  //throw new Error(`Invalid [${index}] [${actual}] item. Each inventor on the list should be pushed as the [${expected}] item.`);
});

Return value

The function type() returns true when all items of the actual array are of valid types.
The function type() returns false when at least one of the checked items is of invalid type.

const valid = type(['Nikola', 'Albert'], [Object, null], () => {
  console.log('Aborted.');
});
if(!valid) return;

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