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 v1.0.0

Additional type checks for check-types.js

See Readable conditions for advice and examples.

Install

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

// instead of
var check = require('check-types');
// use this
var check = require('check-more-types');
console.assert(check.bit(1), 'check.bit works');

browser bower install check-more-types --save

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

• API
  • check.bit
  • check.same
  • check.allSame
  • check.unit
  • check.hexRgb
  • check.bool
  • check.emptyString
  • check.empty
  • check.unempty
  • check.unemptyArray
  • check.arrayOfStrings
  • check.arrayOfArraysOfStrings
  • check.lowerCase
  • check.has(obj, property)
  • check.all
  • check.schema
  • check.schema bind
  • schema composition
  • check.raises(fn, validator)
• Modifiers
  • check.maybe
  • check.not
  • check.verify
• Adding your own predicates
  • check.mixin(predicate, name)
  • check.mixin does not override
• Defending a function
  • check.defend(fn, predicates)
  • protects optional arguments
  • check.defend with messages
  • check.defend in module pattern
• Safe callback execution
  • check.then

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.doesNotExist); // false
check.defined({}.doesNotExist); // false

---

check.bit

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

---

check.same

var foo = {},
  bar = {};
check.same(foo, foo); // true
check.same(foo, bar); // false
// primitives are compared by value
check.same(0, 0); // true
check.same('foo', 'foo'); // true

check.same should produce same result as ===.

check.allSame

var foo = {},
  bar = {};
check.allSame([foo, foo, foo]); // true
check.allSame([foo, foo, bar]); // false
// primitives are compared by value
check.allSame([0, 0]); // true
check.allSame(['foo', 'foo', 'foo']); // true
check.allSame([false, 0]); // false

---

check.unit

check.unit(0); // true
check.unit(1); // true
check.unit(0.1); // true
check.unit(1.2); // false
check.unit(-0.1); // false

---

check.hexRgb

check.hexRgb('#FF00FF'); // true
check.hexRgb('#000'); // true
check.hexRgb('#aaffed'); // true
check.hexRgb('#00aaffed'); // false
check.hexRgb('aaffed'); // 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.emptyString

check.emptyString(''); // true
check.emptyString(' '); // false
check.emptyString(0); // false
check.emptyString([]); // false

---

check.empty

check.empty([]); // true
check.empty(''); // true
check.empty({}); // true
check.empty(0); // false
check.empty(['foo']); // false

---

check.unempty

check.unempty([]); // false
check.unempty(''); // false
check.unempty({}); // false
check.unempty(0); // true
check.unempty(['foo']); // true
check.unempty('foo'); // true

---

check.unemptyArray

check.unemptyArray(null); // false
check.unemptyArray(1); // false
check.unemptyArray({}); // false
check.unemptyArray([]); // false
check.unemptyArray(root.doesNotExist); // 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.schema

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

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

Because bound schema parameter generates a valid function, you can nest checks using schema composition. For example let us combine the reuse isValidPerson as part of another check

schema composition

var teamSchema = {
  manager: isValidPerson,
  members: check.unemptyArray
};
var team = {
  manager: {
    name: 'jim',
    age: 20
  },
  members: ['joe', 'ann']
};
check.schema(teamSchema, team); // true

---

check.raises(fn, validator)

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

function bar() {}

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

function isInvalid(err) {
  check.instance(err, Error); // true
  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

check.mixin(predicate, name)

function isBar(a) {
  return a === 'bar';
}
check.mixin(isBar, 'bar');
check.bar('bar'); // true
check.bar('anything else'); // false
// supports modifiers
check.maybe.bar(); // true
check.maybe.bar('bar'); // true
check.not.bar('foo'); // true
check.not.bar('bar'); // false

Mixin will not override existing functions

check.mixin does not override

function isFoo(a) {
  return a === 'foo';
}

function isBar(a) {
  return a === 'bar';
}
check.mixin(isFoo, 'isFoo');
check.isFoo; // isFoo
check.mixin(isBar, 'isFoo');
check.isFoo; // isFoo

Defending a function

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

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'
// calling safeAdd('foo', 2) raises an exception
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'

---

You can add extra message after a predicate

check.defend with messages

function add(a, b) {
  return a + b;
}
var safeAdd = check.defend(add, check.number, 'a should be a number', check.string, 'b should be a string');
safeAdd(2, 'foo'); // '2foo'
function addNumbers() {
  return safeAdd(2, 3);
}

function checkException(err) {
  err.message; // 'Argument 2: 3 does not pass predicate: b should be a string'
  return true;
}
check.raises(addNumbers, checkException); // true

---

This works great when combined with JavaScript module pattern as in this example

check.defend in module pattern

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);
}());
add(2, 3); // 5
// trying to call with non-numbers raises an exception
function callAddWithNonNumbers() {
  return add('foo', 'bar');
}
check.raises(callAddWithNonNumbers); // true

---

Safe callback execution

Sometimes we want to execute a function depending on the condition, but without throwing an exception. For these cases, there is check.then

check.then

function isSum10(a, b) {
  return a + b === 10;
}

function sum(a, b) {
  return a + b;
}
var onlyAddTo10 = check.then(isSum10, sum);
// isSum10 returns true for these arguments
// then sum is executed
onlyAddTo10(3, 7); // 10
onlyAddTo10(1, 2); // undefined
// sum is never called because isSum10 condition is false

---

Small print

Author: Kensho © 2014

• @kensho
• kensho.com

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

This documentation was generated using grunt-xplain and grunt-readme.

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.