typeof-properties

v3.1.3

Published

2 years ago

Validate the type of object's properties.

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devrafalko

typeof object validation validate property properties value type undefined instanceof

Description

typeof-properties validates the object's properties' 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.

Implementation

with NodeJS

npm install typeof-properties

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

with Browser

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

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

<head>
  <script src='typeof-properties.js'></script>
  <script>
    var person = { name: 'Nikola', age: 26 }
    typeofProperties(person, { name: String, age: 'number' });
  </script>
</head>

Tests

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

Usage

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

`actual` [Object]

It should indicate the [Object]
The properties of actual object will be validated.

`expected` [Object]

The expected object should contain properties, that cohere with the properties of actual object
The values of expected object's properties should indicate the expected type of the coherent properties of actual object
If some of the actual properties are ommited in expected object, they will not be validated (can be of any type)

The `expected` Types

There are four ways to check the type of properties:

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-properties 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

const actual = {
  name: 'Nikola',
  age: 26
};

const expected = {
  name: 'string',
  age: 'number|string|undefined'
};

type(actual, expected);

[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

const actual = {
  name: 'Nikola',
  age: 26
};

const expected = {
  name: /string/i,
  age: /Number|String|undefined/
};

type(actual, expected);

[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]

const actual = {
  name: 'Nikola',
  age: 26
};

const expected = {
  name: String,
  age: [Number, String, undefined]
};

type(actual, expected);

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 and eg.
type({name: new Name('Nikola')}, {name: 'Name'});
that is valid before compilation, may fail after compilation, if the bundler minifies the 'Name' constructor name.

Extra types:

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

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

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

The type 'instance' or /instance/ expects the property's value to be the instance of the user's class|constructor
It fails when the property's value 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 property's value to be the object that is the instance of the Object constructor
- {}, [], new String('hello world'), new Boolean(1)
It fails when the property's value 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 property's value to be like:
- 'abc', true, 1, -1, {}, [], function(){}

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

The type 'falsy' or /falsy/ expects the property's value 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 property's value to be of any type

`callback` [Function] (optional)

if not passed, the TypeError with default message will be thrown to the console, if the property value type is invalid.
The TypeError default message is eg.:
- Invalid property ["name"]. The [undefined] value has been assigned, while the value of type matching string expression "string|null" is expected.
- Invalid property ["name"]. The [undefined] <<falsy>> value has been assigned, while the value of type matching string expression "truthy|null" is expected.
- Invalid property ["name"]. The [undefined] value has been assigned, while the value of type matching regular expression /String|null/ is expected.
- Invalid property ["name"]. 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 property's value is of invalid type.
The one [Object] argument is passed through callback function with the following properties:
- name
  indicates the [String] name of the incorrect property, eg. "name", "age"
- actual
  indicates the actual type of the property's value, eg. "String"
- 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-properties');

const person = {
  name: 'Nikola',
  age: '27',
  experience: 7,
  male: true,
  skills: ['js', 'nodejs', 'mongodb'],
  talk: function () {
    return `hello I'm ${this.name}`;
  }
};

const validation = {
  name: 'string',
  age: /(number|string)/i,
  talk: 'function|falsy',
  skills: [Array, Object, null],
  male: Boolean
  //experience property is ommited - not validated - can be of any type
};

type(person, validation, (o) => {
  console.error(o.message);
  /*
  console.error(`Not good! Use ${o.expected} instead of ${o.actual} for the property ${o.name}`);
  throw new TypeError('Aborted: ' + o.message); 
  */
});

Return value

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

if (!type(person, validation, () => console.log('Aborted.'))) return;

Samples

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

const weatherData = {
  city: 'Warsaw',
  latitude: 52.229676,
  longitude: 21.012229,
  date: new Date('2017-08-22'),
  temperature: { day: 24, night: 18 },
  humidity: .71,
  winter: { kph: 18, mph: 11.3 }
};

const weatherValid = {
  city: 'string',
  latitude: [Number, String],
  longitude: [Number, String],
  date: 'date',
  temperature: /object|number/i,
  humidity: 'number|falsy',
  winter: 'object|number'
};

const tempValid = {
  day: 'number|undefined',
  night: [Number, undefined]
};

const winterValid = {
  kph: 'number|falsy',
  mph: /number|falsy/i
};

type(weatherData, weatherValid);
type(weatherData.temperature, tempValid);
type(weatherData.winter, winterValid);

more samples

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

class Person {
  constructor(name, age, earnings) {
    this.name = name;
    this.age = age;
    this.earnings = earnings;
  }
}

class Earnings {
  constructor(income, tax) {
    this.income = income;
    this.tax = tax;
  }
}

const earnings = new Earnings(23000, 6400);
const person = new Person('Jessica', 22, earnings);

const expected = {
  name: String,
  age: 'number',
  earnings: 'instance'
};

type(person, expected);

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