check-more-types

Large collection of predicates, inspired by check-types.js

See Readable conditions for advice and examples.

Install

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

var check = require('check-more-types');
console.assert(check.bit(1), 'check.bit works');

browser bower install check-more-types --save

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

API
Modifiers
Adding your own predicates
- check.mixin(predicate, name)
- check.mixin does not override
Defending a function
Safe callback execution

check.number

check.number is part of the check-types library, but as a note, it does not pass null, undefined or NaN values

check.number(null); // false
check.not.number(undefined); // true
check.number(NaN); // false

check.email

Really simple regex email check. Should not be relied to be robust.

check.email('me@foo.bar') // true
check.email('me.foo.bar') // false

check.extension (alias `check.ext`)

Confirms that given file name has expected extension

check.extension('txt', 'foo/bar.txt') // true

It is curried, so you can create convenient methods

const isJs = check.extension('js')
isJs('script.js') // true

There are a couple of convenient shortcuts, like check.isJs, check.isJson, check.isJpg

check.odd and check.even

Check if a number odd or even

check.odd(2) // false
check.odd(3) // true
check.even(2) // true

check.port

Returns true if passed argument is positive number less or equal to largest allowed port number 65535

check.systemPort

Returns true if passed argument is number between 0 and 1024

check.userPort

Returns true if passed argument is a port number and larger than 1024

check.error

Returns true if given argument is an instance of type Error

check.https (alias `secure`)

Returns true if the provided url starts with https://. Alias secure.

check.http

Returns true if the provided url starts with http://

check.webUrl (alias `url`)

Returns true if the given string is http or https url.

check.contains

Returns true if given array contains an item, or given string contains substring.

check.contains(['foo', 42], 'foo'); // true
check.contains('apple', 'pp'); // true

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.semver

check.semver('1.0.2'); // true
check.semver('1.0.2-alpha'); // false

check.positiveNumber (alias `check.positive`)

check.positive(100); // true
check.not.positive(-1); // true

check.negativeNumber (alias `check.negative`)

check.negative(-10); // true
check.not.negativeNumber(1); // true

check.type

check.type('string', 'foo'); // true
check.type('number', 42); // true

check.type is curried.

check.bit

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

check.primitive

Returns true for primitive JavaScript types

check.primitive(42); // true
check.primitive(true); // true
check.primitive('foo'); // true
check.primitive([]); // false

Also returns true for Symbol ES6 syntax.

check.zero

check.zero(0); // true
check.zero(); // false
check.zero(null); // false

check.git

check.git('url string');

check.commitId

check.shortCommitId

check.index

check.oneOf

var colors = ['red', 'green', 'blue'];
var color = 'green';
check.oneOf(colors, color); // true
check.oneOf(colors, 'brown'); // false

Function is curried

check.same

var foo = {}
var 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.length

Confirms length of a string or an Array. The function is curried and can guess the argument order

check.length([1, 2], 2); // true
check.length('foo', 3); // true
// argument order
check.length(3, 'foo'); // true
// curried call
check.length('foo')(3); // true
check.length(3)('foo'); // true

check.sameLength

check.sameLength([1, 2], ['a', 'b']); // true
check.sameLength('ab', 'cd'); // true
// different types
check.sameLength([1, 2], 'ab'); // false

check.allSame

var foo = {}
var 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 (alias `strings`)

// 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.numbers

Returns true if all items in an array are numbers

check.arrayOf

check.arrayOf(check.unemptyString, ['foo', '']); // false
check.arrayOf(check.unemptyString, ['foo', 'bar']); // true
// can be partially applied and combined with check.schema
var person = {
  first: check.unemptyString,
  last: check.unemptyString
};
var isPerson = check.schema.bind(null, person);
var arePeople = check.arrayOf.bind(null, isPerson);
var people = [{
  first: 'foo',
  last: 'bar'
}];
arePeople(people); // true

Why would you need check.arrayOf(predicate, x) and not simply use x.every(predicate)? Because x might not be an Array.

check.badItems

Finds items that do not pass predicate

check.badItems(check.unemptyString, ['foo', '', 'bar']); // ['']

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

The method is curried, thus you can easily create predicate function

var hasName = check.schema({ name: check.unemptyString });
hasName({ name: 'joe' }); // true

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

If you want you can manually bind check.schema to first argument

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

You can use Function.prototype.bind or any partial application method, for example _.partial(check.schema, personSchema);. 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. If you do not pass a name, it will try using function's name.

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

check.found

Great for quickly checking string or array search results

check.found('foo'.indexOf('f')); // true
check.found('foo bar'.indexOf('bar')); // true

check.regexp

Returns true if the passed value is a regular expression.

check.promise

Returns true if given object has promise methods (.then, etc)

check.validDate

Returns true if the given instance is a Date and is valid.

check.equal

Curried shallow strict comparison

var foo = 'foo';
check.equal(foo, 'foo'); // true
var isFoo = check.equal('foo');
isFoo('foo'); // true
isFoo('bar'); // false

check.or

Combines multiple predicates into single one using OR logic

var predicate = check.or(check.bool, check.unemptyString);
predicate(true); // true
predicate('foo'); // true
predicate(42); // false

It treats non-functions as boolean values

var predicate = check.or(check.unemptyString, 42);
// will always return true
predicate('foo'); // true, because it is unempty string
predicate(false); // true, because 42 is truthy

Note: if there are any exceptions inside the individual predicate functions, they are treated as false values.

check.and

Combines multiple predicates using AND. If the predicate is not a function, evaluates it as a boolean value.

function isFoo(x) { return x === 'foo'; }
check.and(check.unemptyString, isFoo); // only true for "foo"

Both check.or and check.and are very useful inside check.schema to create more powerful predicates on the fly.

var isFirstLastNames = check.schema.bind(null, {
  first: check.unemptyString,
  last: check.unemptyString
});
var isValidPerson = check.schema.bind(null, {
  name: check.or(check.unemptyString, isFirstLastNames)
});
isValidPerson({ name: 'foo' }); // true
isValidPerson({ name: {
  first: 'foo',
  last: 'bar'
}}); // true

Small print

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)

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.

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kensho-technologies/check-more-types

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