check-more-types

What is check-more-types?

The check-more-types npm package provides a variety of type checking and assertion functions that enhance JavaScript's type testing capabilities. It offers a wide range of predicates for more precise type validation, making it easier to enforce type safety in JavaScript applications.

What are check-more-types's main functionalities?

Primitive type checks

This feature allows for checking JavaScript's primitive types such as strings, numbers, and booleans. It's useful for basic type validation.

const check = require('check-more-types');

// checks if a value is a string
check.string('hello'); // true

// checks if a value is a number
check.number(42); // true

Complex type checks

This feature extends the library's capabilities to more complex types, such as arrays of specific types or objects matching a schema. It's particularly useful for validating data structures.

const check = require('check-more-types');

// checks if a value is an array of strings
check.arrayOfStrings(['hello', 'world']); // true

// checks if a value is an object with specific properties
check.schema({
  name: check.string,
  age: check.number
})({ name: 'John', age: 30 }); // true

Custom predicates

check-more-types allows for the creation of custom predicates, enhancing its flexibility and allowing users to define their own specific type checks.

const check = require('check-more-types');

// defines a custom predicate for checking if a number is even
check.mixin({
  even: function (n) { return check.number(n) && n % 2 === 0; }
});

// uses the custom predicate
check.even(42); // true

Other packages similar to check-more-types

joi

Joi is a powerful schema description language and data validator for JavaScript. Compared to check-more-types, Joi offers a more comprehensive API for defining complex validation schemas, making it better suited for validating nested objects and complex data structures.

prop-types

Prop-types is a library for type checking React component props. While check-more-types is more general-purpose, prop-types is specifically designed for React applications, offering a straightforward way to ensure components receive props of the correct type.

validator

Validator is a library that provides string validation and sanitization. Unlike check-more-types, which offers a broad range of type checks, Validator focuses on string validation, offering functions for format validation, sanitization, and more.

README

check-more-types v0.8.0

Additional type checks for check-types.js

Install

node: npm install check-more-types --save

global.check = require('check-types');
require('check-more-types');
// patches global check object

browser bower install check-more-types --save

<script src="check-types.js"></script>
<script src="check-more-types.js"></script>

See Readable conditions for examples.

API

check.defined

check.defined(0); // true
check.defined(1); // true
check.defined(true); // true
check.defined(false); // true
check.defined(null); // true
check.defined(''); // true
check.defined(); // false
check.defined(root.does_not_exist); // false
check.defined({}.does_not_exist); // false

---

check.bit

check.bit(0); // true
check.bit(1); // true
check.bit('1'); // false
check.bit(2); // false
check.bit(true); // false

---

check.bool

check.bool(true); // true
check.bool(false); // true
check.bool(0); // false
check.bool(1); // false
check.bool('1'); // false
check.bool(2); // false

---

check.unemptyArray

check.unemptyArray(null); // false
check.unemptyArray(1); // false
check.unemptyArray({}); // false
check.unemptyArray([]); // false
check.unemptyArray(root.does_not_exist); // false
check.unemptyArray([1]); // true
check.unemptyArray(['foo', 'bar']); // true

---

check.arrayOfStrings

// second argument is checkLowerCase
check.arrayOfStrings(['foo', 'Foo']); // true
check.arrayOfStrings(['foo', 'Foo'], true); // false
check.arrayOfStrings(['foo', 'bar'], true); // true
check.arrayOfStrings(['FOO', 'BAR'], true); // false

---

check.arrayOfArraysOfStrings

// second argument is checkLowerCase
check.arrayOfArraysOfStrings([['foo'], ['bar'}}); // true
check.arrayOfArraysOfStrings([['foo'], ['bar'}}, true); // true
check.arrayOfArraysOfStrings([['foo'], ['BAR'}}, true); // false

---

check.lowerCase

check.lowerCase('foo bar'); // true
check.lowerCase('*foo ^bar'); // true
check.lowerCase('fooBar'); // false
// non-strings return false
check.lowerCase(10); // false

---

check.has(obj, property)

var obj = {
  foo: 'foo',
  bar: 0
};
check.has(obj, 'foo'); // true
check.has(obj, 'bar'); // true
check.has(obj, 'baz'); // false
// non-object returns false
check.has(5, 'foo'); // false
check.has('foo', 'length'); // true

---

check.all

var obj = {
  foo: 'foo',
  bar: 'bar',
  baz: 'baz'
};
var predicates = {
  foo: check.unemptyString,
  bar: function(value) {
    return value === 'bar';
  }
};
check.all(obj, predicates); // true

---

check.spec is equivalent to check.all but with arguments reversed. This makes it very convenient to create new validator functions using partial argument application

check.schema bind

var personSchema = {
  name: check.unemptyString,
  age: check.positiveNumber
};
var isValidPerson = check.schema.bind(null, personSchema);
var h1 = {
  name: 'joe',
  age: 10
};
var h2 = {
  name: 'ann'
  // missing age property
}
isValidPerson(h1); // true
isValidPerson(h2); // false

---

check.raises(fn, validator)

function foo() {
  throw new Error('foo');
}

function bar() {}

function isValidError(err) {
  return err.message === 'foo';
}

function isInvalid(err) {
  return false;
}
check.raises(foo); // true
check.raises(bar); // false
check.raises(foo, isValidError); // true
check.raises(foo, isInvalid); // false

Modifiers

Every predicate function is also added to check.maybe object. The maybe predicate passes if the argument is null or undefined, or the predicate returns true.

check.maybe

check.maybe.bool(); // true
check.maybe.bool('true'); // false
var empty;
check.maybe.lowerCase(empty); // true
check.maybe.unemptyArray(); // true
check.maybe.unemptyArray([]); // false
check.maybe.unemptyArray(['foo', 'bar']); // true

Every function has a negated predicate in check.not object

check.not

check.not.bool(4); // true
check.not.bool('true'); // true
check.not.bool(true); // false

Every predicate can also throw an exception if it fails

check.verify

check.verify.arrayOfStrings(['foo', 'bar']);
check.verify.bit(1);

function nonStrings() {
  check.verify.arrayOfStrings(['Foo', 1]);
}
check.raises(nonStrings); // true
function nonLowerCase() {
  check.verify.lowerCase('Foo');
}
check.raises(nonLowerCase); // true

---

Adding your own predicates

You can add new predicates to check, check.maybe, etc. by using check.mixin(predicate) method

Defending a function

Using check-more-types you can separate the inner function logic from checking input arguments. Instead of this

:::javascript
function add(a, b) {
    la(check.number(a), 'first argument should be a number', a);
    la(check.number(a), 'second argument should be a number', b);
    return a + b;
}

you can use check.defend function

check.defend(fn, predicates)

function add(a, b) {
  return a + b;
}
var safeAdd = check.defend(add, check.number, check.number);
add('foo', 2); // 'foo2'
check.raises(safeAdd.bind(null, 'foo', 2)); // true

---

protects optional arguments

function add(a, b) {
  if (typeof b === 'undefined') {
    return 'foo';
  }
  return a + b;
}
add(2); // 'foo'
var safeAdd = check.defend(add, check.number, check.maybe.number);
safeAdd(2, 3); // 5
safeAdd(2); // 'foo'

---

This works great when combined with JavaScript module pattern

:::javascript
var add = (function () {
    // inner private function without any argument checks
    function add(a, b) {
        return a + b;
    }
    // return defended function
    return check.defend(add, check.number, check.number);
}());

Small print

Author: Kensho © 2014

• @kensho
• kensho.com

Support: if you find any problems with this library, open issue on Github

MIT License

The MIT License (MIT)

Copyright (c) 2014 Kensho

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.