predicate.jsv. 1.0.0

Adding clarity and conciseness to your JS through predicates

predicate provides a slew of functions that allow you to compare values and test types. This leads to more functional, concise, legible, and correct code.

This is extremely useful when filtering data or comparing against a set of data.

  ['venus', 'neptune', 1, []].filter(predicate.str); // ['venus', 'neptune']
  [1.2, 3, 5].every(predicate.int) // false

is also offers autocurrying for predicates of arity 2

var isInSet = predicate.contains([1, 2, 3]);
isInSet(1); // true
isInSet(5); // false

var hasKey = predicate.has({ name: 'Trevor', twitter: '@trevor_landau' });
hasKey('name'); // true
hasKey('myspace'); // false

Make room on your utility belt next to underscore

  _.filter([1, 2, 3], predicate.less(1)); // [2, 3]
  _.partition([1, -2, -3, 4], predicate.pos); // [[1, 4], [-2, -3]]

The project is hosted on GitHub. You can report bugs and discuss features on the issues page or send tweets to @trevor_landau.

Install/Downloads

Node npm install --save is-predicate

Development predicate.js

Production predicate.min.js

Predicates

not`predicate.not`

A complemented version of the predicate predicate functions. All predicate functions are available in this namespace.

Example

predicate.null(null) // true
predicate.not.null(null) // false

is`predicate.is(a, b)`

Returns true if Object.is(a, b)

curryable

Example

predicate.is(window, window) // true
predicate.is(1, 1) // true
predicate.is(NaN, 0/0) // true
predicate.is(0, -0) // false
predicate.is([], []) // false

exists`predicate.exists(val)`

Returns true if a value is not null or undefined

Example

predicate.exists(null) // false
predicate.exists(false) // true
predicate.exists(0) // true
predicate.exists('javascript') // true

truthy`predicate.truthy(val)`

Returns true if a value exists and isn't false

Example

predicate.truthy(0) // true
predicate.truthy([1, 2]) // true
predicate.truthy(false) // false
predicate.truthy(null) // false

falsey`predicate.falsey(val)`

Returns true if a value is false or doesn't exist

Example

predicate.falsey(0) // false
predicate.falsey([1, 2]) // false
predicate.falsey(false) // true
predicate.falsey(null) // true

null`predicate.null(val)`

Returns true if a value is null

Example

predicate.null(null) // true
predicate.null(false) // false
predicate.null(undefined) // false

undef`predicate.undef(val)`

Returns true if a value is undefined

Example

predicate.undef(undefined) // true
predicate.undef(null) // false
predicate.undef(false) // false

equal`predicate.equal(a, b)`

Returns true if a === b

curryable

Example

predicate.equal(1, 1) // true
predicate.equal('a', 'a') // true
predicate.equal(null, 1) // false
predicate.equal([1, 2], [1, 2]) // false

eq`predicate.eq(a, b)`

Returns true if a == b

curryable

Example

predicate.eq('1', 1) // true
predicate.eq('a', 'b') // false

less`predicate.less(a, b)`

aliaspredicate.lt(a, b)

Returns true if a < b

curryable

Example

predicate.less(1, 5) // true
predicate.less(5, 5) // false
predicate.less(5, 1) // false

lessEq`predicate.lessEq(a, b)`

aliaspredicate.ltEq(a, b) predicate.le(a, b)

Returns true if a <= b

curryable

Example

predicate.lessEq(1, 5) // true
predicate.lessEq(5, 5) // true
predicate.lessEq(5, 1) // false

greater`predicate.greater(a, b)`

aliaspredicate.gt(a, b)

Returns true if a > b

curryable

Example

predicate.greater(5, 1) // true
predicate.greater(5, 5) // false
predicate.greater(1, 5) // false

greaterEq`predicate.greaterEq(a, b)`

aliaspredicate.gtEq(a, b) predicate.ge(a, b)

Returns true if a > b

curryable

Example

predicate.greaterEq(5, 1) // true
predicate.greaterEq(5, 5) // true
predicate.greaterEq(1, 5) // false

object`predicate.object(val)`

aliaspredicate.obj(val)

Returns true if val is an object

Example

predicate.object({}) // true
predicate.object([]) // true
predicate.object(1) // false

array`predicate.array(val)`

aliaspredicate.arr(val)

Returns true if val is an array

Defaults to native Array.isArray

Example

predicate.array([]) // true
predicate.array({}) // false
predicate.array(1) // false

date`predicate.date(val)`

Returns true if val is a date

Example

predicate.date(new Date()) // true
predicate.date({}) // false
predicate.date(1) // false

rgx`predicate.rgx(val)`

aliaspredicate.RegExp(val) predicate.regexp(val) predicate.regex(val)

Returns true if val is a rgx

Example

predicate.rgx(/\d{1,4}/) // true
predicate.rgx(new RegExp("Cosmos", "gi")) // true
predicate.rgx({}) // false
predicate.rgx("Dark Star") // false

finite`predicate.finite(val)`

Returns true if val is a number and isFinite

Example

predicate.finite(1) // true
predicate.finite(2e64) // true
predicate.finite(NaN) // false
predicate.finite('1') // false
predicate.finite(Infinity) // false

nan`predicate.nan(val)`

aliaspredicate.NaN(val)

Returns true if val is NaN

Example

predicate.nan(nan) // true
predicate.nan("titan") // false
predicate.nan(1) // false

arguments`predicate.arguments(val)`

Returns true if val is an arguments object

Example

predicate.arguments(arguments) // true
predicate.arguments("titan") // false

error`predicate.error(val)`

Returns true if val is an error object

Example

predicate.error(new Error()) // true
predicate.error("titan") // false

fn`predicate.fn(val)`

aliaspredicate.function(val)

Returns true if typeof val === 'function'

Example

predicate.fn(predicate.fn) // true
predicate.fn(Math.max) // true
predicate.fn({}) // false
predicate.fn("Dark Star") // false

num`predicate.num(val)`

aliaspredicate.number(val)

Returns true if typeof val === 'number'

Example

predicate.num(1) // true
predicate.num(NaN) // false
predicate.num({}) // false
predicate.num("Dark Star") // false

str`predicate.str(val)`

aliaspredicate.string(val)

Returns true if typeof val === 'string'

Example

predicate.str("Dark Star") // true
predicate.str(1) // false
predicate.str({}) // false

bool`predicate.bool(val)`

aliaspredicate.boolean(val)

Returns true if typeof val === 'boolean'

Example

predicate.bool(true) // false
predicate.bool(false) // false
predicate.bool("Dark Star") // false
predicate.bool(1) // false

int`predicate.int(val)`

Returns true if val is an integer

Example

predicate.int(1) // true
predicate.int(1.5) // false

primitive`predicate.primitive(val)`

Returns true if val is a primitive value

Example

predicate.primitive(1) // true
predicate.primitive('a') // true
predicate.primitive(null) // true
predicate.primitive(NaN) // true
predicate.primitive([]) // false
predicate.primitive({}) // false

pos`predicate.pos(val)`

Returns true if val > 0 and is a number

Example

predicate.pos(1) // true
predicate.pos(-2) // false
predicate.pos(0) // false

neg`predicate.neg(val)`

Returns true if val < 0 and is a number

Example

predicate.neg(-2) // true
predicate.neg(1) // false
predicate.neg(0) // false

zero`predicate.zero(val)`

Returns true if val === 0 and is a number

Example

predicate.zero(0) // true
predicate.zero(-2) // false
predicate.zero(1) // false

even`predicate.even(val)`

Returns true if val is a number, not zero, and it's modulus of 2 is zero

Example

predicate.even(2) // true
predicate.even(0) // false
predicate.even(1) // false

odd`predicate.odd(val)`

Returns true if val is a number, not zero, and it's modulus of 2 is not zero

Example

predicate.odd(1) // true
predicate.odd(2) // false
predicate.odd(0) // false

includes`predicate.includes(arr, val)`

aliaspredicate.contains(arr, val)

Returns true if val exists in arr

curryable

Example

var arr = [1, 2, 3, 4];
predicate.includes(arr, 2) // true
predicate.includes(arr, -5) // false

empty`predicate.empty(o)`

Returns true if o is an object and has no owned props

Returns true if o is an array or string of length zero

Throws TypeError if o is not an Array, Object, or String

Example

predicate.empty([]) // true
predicate.empty(['a']) // false
predicate.empty({}) // true
predicate.empty({foo: 'bar'}) // false

has`predicate.has(o, key)`

Returns true if string key exists on object o

curryable

Example

var o = { planet: 'Earth' };
predicate.has(o, 'planet') // true
predicate.has(o, 'moon') // false

instance`predicate.instance(Cls, [inst])`

Returns true if inst instanceof Cls is true.

curryable

Example

function Planet() {}
var p = new Planet();

var isPlanet = predicate.instance(Planet);
isPlanet(p); // true
predicate.instance(Planet, p); // true

matches`predicate.matches(rgx, val)`

Returns rgx.test(val)

curryable

Example

var rgx = /\d{3}/;
predicate.matches(rgx, 200) // true
predicate.matches(rgx, 50) // false

ternary`predicate.ternary(pred, [a [b]])`

If a pred is given:

Returns a function(a, b) that evaluates pred(a, b)

If pred and a and is given:

Returns a function(b) that evaluates pred(a, b)

If pred and a and b is given:

Returns the evaluation of pred(a, b)

If pred is of type boolean, a, and b are given

Returns bool ? a : b

Example

var pred1 = predicate.ternary(predicate.less);
pred1(1, 2); // 1

var pred2 = predicate.ternary(predicate.less, 1);
pred2(2); // 1

predicate.ternary(predicate.less, 1, 2); // 1
predicate.ternary(1 < 2, 'a', 'b'); // 'a'

and`predicate.and([p1, p2, ...pN])`

Returns a function in which, when evaluated with val, returns true if all given predicates return true.

Example

var fn = predicate.and(predicate.less(3), predicate.greater(1));
fn(2); // true

or`predicate.or([p1, p2, ...pN])`

Returns a function in which, when evaluated with val, returns true if at least one of the given predicates return true.

Example

var fn = predicate.or(predicate.less(3), predicate.greater(1));
fn(1); // true

Chaining

every`predicate.every()`

aliaspredicate.all()

Returns a chainable interface for lazily executing predicates.

Invoke .val() which returns true if all predicates evaluate to true.

Example

var chain = predicate.every();
chain = chain.less(1, 2).fn(predicate.exists);
chain.val(); // true
chain.NaN(1).val(); // false

predicate.every().exists('mars').str('asteroid').val(); //true

some`predicate.some()`

aliaspredicate.any()

Returns a chainable interface for lazily executing predicates.

Invoke .val() which returns true if at least 1 predicate evaluate to true.

Example

var chain = predicate.some();
chain = chain.equal(1, 2).fn(predicate.exists);
chain.val(); // true
chain.NaN(1).val(); // true

predicate.some().exists(null).str('asteroid').val(); // true
predicate.some().exists(null).str(1).val(); // false

Utils

curry`predicate.curry(fn)`

Returns a new function that curries a given fn.

Used internally

Example

var fn = predicate.curry(function add(a, b) {
  return a + b;
});
var fn2 = add(1);

fn2(2); // 3
fn2(5); // 6
fn(2, 2); // 4

partial`predicate.partial(fn, ...)`

Returns a partially applied function based on fn.

Used internally

Example

var fn = predicate.partial(predicate.less, 1);
fn(2); // true

complement`predicate.complement(fn)`

aliaspredicate.invert(fn)

Returns a function a that receives the same args as fn and returns the opposite truth value.

Used internally

Example

var fn = predicate.complement(predicate.fn);
fn(predicate.fn); // false

mod`predicate.mod(a, b)`

Returns the value of a % b

Used internally

Example

predicate.mod(6, 5); // 1
predicate.mod(6, 6); // 0

changelog

1.2.0

Add support for searching strings using includes
Use native Object.assign when available

1.1.2

Add includes as alias to contains

1.1.1

Improve perf around chaining methods

1.1.0

add and and or functions

1.0.0

Convert to nodejs 4.x es6 support

0.12.0

Add predicate.matches

0.11.0

Add alias predicate.nan
Add alias predicate.regex and predicate.regexp
Add alias predicate.le
Add alias predicate.ge

0.10.2

Changed from is.js to predicate.js

0.10.0

Added is.primitive (@tgriesser)
Update docs with is.empty (@BlaineBublitz)
is.empty now throws for invalid types

0.9.0

Added is.is based off polyfill from MDN
Added alias for is.object and is.arr
is.num(NaN) now returns false

0.8.2

Correctly test for NaN in is.contains

0.8.1

Fix currying issue with is.not

0.8.0

Added is.curry which is used internally
Added autocurrying for all functions that are arity 2
is.complement can now return a function instead of just booleans
is.truthy and is.falsey now respect js falsey values (eg 0, '', etc)

0.7.3

Refactored file structure

0.7.2

Update docs

0.7.1

Converted module to node style package
build process uses browserify standalone
Tests now in JS instead of CS (run much faster!)
Internal changes around chaining
Dropped gulp

0.7.0

Added even, odd
Exposed mod
Even more improved docs!

0.6.0

Removed cmp
Added is.empty
Alias is.invert as is.complement
Expose is.partial from internals
Improved docs

0.5.0

Added is.zero
Fix is.object and is.error
is.ternary now supports partial application
is.gt, is.gtEq, is.lt, is.ltEq aliases added

0.4.0

Support for lazy chain evaluation

0.3.0

Expose `is.invert
Added `is.contains
Added `is.has
Remove bower support

0.2.0

Added is.pos
Added is.neg
Added is.ternary
Added is.not, which inverses all boolean returning predicate methods

0.1.1

Added is.bool/boolean method

0.1.0

Release

predicate.jsv. 1.0.0

Adding clarity and conciseness to your JS through predicates

Install/Downloads

Predicates

notpredicate.not

ispredicate.is(a, b)

existspredicate.exists(val)

truthypredicate.truthy(val)

falseypredicate.falsey(val)

nullpredicate.null(val)

undefpredicate.undef(val)

equalpredicate.equal(a, b)

eqpredicate.eq(a, b)

lesspredicate.less(a, b)

lessEqpredicate.lessEq(a, b)

greaterpredicate.greater(a, b)

greaterEqpredicate.greaterEq(a, b)

objectpredicate.object(val)

arraypredicate.array(val)

datepredicate.date(val)

rgxpredicate.rgx(val)

finitepredicate.finite(val)

nanpredicate.nan(val)

argumentspredicate.arguments(val)

errorpredicate.error(val)

fnpredicate.fn(val)

numpredicate.num(val)

strpredicate.str(val)

boolpredicate.bool(val)

intpredicate.int(val)

primitivepredicate.primitive(val)

pospredicate.pos(val)

negpredicate.neg(val)

zeropredicate.zero(val)

evenpredicate.even(val)

oddpredicate.odd(val)

includespredicate.includes(arr, val)

emptypredicate.empty(o)

haspredicate.has(o, key)

instancepredicate.instance(Cls, [inst])

matchespredicate.matches(rgx, val)

ternarypredicate.ternary(pred, [a [b]])

andpredicate.and([p1, p2, ...pN])

orpredicate.or([p1, p2, ...pN])

Chaining

everypredicate.every()

somepredicate.some()

Utils

currypredicate.curry(fn)

partialpredicate.partial(fn, ...)

complementpredicate.complement(fn)

modpredicate.mod(a, b)

changelog

1.2.0

1.1.2

1.1.1

1.1.0

1.0.0

0.12.0

0.11.0

0.10.2

0.10.0

0.9.0

0.8.2

0.8.1

0.8.0

0.7.3

0.7.2

0.7.1

0.7.0

0.6.0

0.5.0

0.4.0

0.3.0

0.2.0

0.1.1

0.1.0

not`predicate.not`

is`predicate.is(a, b)`

exists`predicate.exists(val)`

truthy`predicate.truthy(val)`

falsey`predicate.falsey(val)`

null`predicate.null(val)`

undef`predicate.undef(val)`

equal`predicate.equal(a, b)`

eq`predicate.eq(a, b)`

less`predicate.less(a, b)`

lessEq`predicate.lessEq(a, b)`

greater`predicate.greater(a, b)`

greaterEq`predicate.greaterEq(a, b)`

object`predicate.object(val)`

array`predicate.array(val)`

date`predicate.date(val)`

rgx`predicate.rgx(val)`

finite`predicate.finite(val)`

nan`predicate.nan(val)`

arguments`predicate.arguments(val)`

error`predicate.error(val)`

fn`predicate.fn(val)`

num`predicate.num(val)`

str`predicate.str(val)`

bool`predicate.bool(val)`

int`predicate.int(val)`

primitive`predicate.primitive(val)`

pos`predicate.pos(val)`

neg`predicate.neg(val)`

zero`predicate.zero(val)`

even`predicate.even(val)`

odd`predicate.odd(val)`

includes`predicate.includes(arr, val)`

empty`predicate.empty(o)`

has`predicate.has(o, key)`

instance`predicate.instance(Cls, [inst])`

matches`predicate.matches(rgx, val)`

ternary`predicate.ternary(pred, [a [b]])`

and`predicate.and([p1, p2, ...pN])`

or`predicate.or([p1, p2, ...pN])`

every`predicate.every()`

some`predicate.some()`

curry`predicate.curry(fn)`

partial`predicate.partial(fn, ...)`

complement`predicate.complement(fn)`

mod`predicate.mod(a, b)`