Go-types NPM | npm.io

Go Types

Type-checking utilities for JavaScript.

version: 1.3.1
license: MIT

Installation

npm i go-types

yarn add go-types

Usage

ES6

import Types from 'go-types'

Types.isArray([]);

import { isArray } from 'go-types';

isArray([]);

Node

const Types = require('go-types');

Types.isArray([]);

const { isArray } = require('go-types');

isArray([]);

Web browser

<script src="dist/go-types.min.js"></script>
<script>
    const { isArray } = Types;

    isArray([]);
</script>

Documentation

Primitive

isUndefined

Determines whether the value is undefined.

Parameters

value any The value to check.

Examples

Undefined values

// returns true
isUndefined(undefined);
isUndefined(void 0);

Non-undefined values

// returns false
isUndefined(null);
isUndefined(false);
isUndefined(0);
isUndefined("");
isUndefined(NaN);

Returns boolean true if the value is undefined; false otherwise.

Meta

since: 1.0.0

isNull

Determines whether the value is null.

Parameters

value any The value to check.

Examples

Null values

// returns true
isNull(null);

Non-null values

// returns false
isNull(undefined);
isNull(false);
isNull(0);
isNull("");
isNull(NaN);

Returns boolean true if the value is null; false otherwise.

Meta

since: 1.0.0

isBoolean

See: Types.isPrimitive
See: Types.isObject
See: Types.isTypeOf

Determines whether the value is a primitive boolean or Boolean object.

Parameters

value any The value to check.

Examples

Boolean values

// returns true
isBoolean(true);
isBoolean(new Boolean(true));

Non-boolean values

// returns false
isBoolean(1);
isBoolean("true");

Returns boolean true if the value is a primitive boolean or Boolean object; false otherwise.

Meta

since: 1.0.0

isNumber

See: Types.isPrimitive
See: Types.isObject
See: Types.isTypeOf

Determines whether the value is a primitive number or Number object which includes the "special" numbers +Infinity, -Infinity and NaN.

Parameters

value any The value to check.

Examples

Number values

// returns true
isNumber(1);
isNumber(-12.34);
isNumber(new Number(1));
isNumber(Infinity);
isNumber(NaN);

Non-number values

// returns false
isNumber("1");
isNumber(true);

Returns boolean true if the value is a primitive number or Number object; false otherwise.

Meta

since: 1.0.0

isString

See: Types.isPrimitive
See: Types.isObject
See: Types.isTypeOf

Determines whether the value is a primitive string or String object.

Parameters

value any The value to check.

Examples

String values

// returns true
isString("1");
isString(new String("abc"));

Non-string values

// returns false
isString(1);
isString(["a", "b"]);

Returns boolean true if the value is a primitive string or String object; false otherwise.

Meta

since: 1.0.0

isSymbol

See: Symbol

Determines whether the value is a primitive Symbol.

Parameters

value any The value to check.

Examples

Symbol values

// returns true
isSymbol(Symbol("abc"));

Non-Symbol values

// returns false
isSymbol("abc");
isSymbol(/[a-z]/);

Returns boolean true if the value is a primitive Symbol; false otherwise.

Meta

since: 1.0.0

isBigInt

See: BigInt

Determines whether the value is a primitive BigInt.

Parameters

value any The value to check.

Examples

BigInt values

// returns true
isBigInt(BigInt(1));
isBigInt(BigInt(-1234567890));

Non-BigInt values

// returns false
isBigInt(Number.MAX_VALUE);
isBigInt(Infinity);
isBigInt(NaN);
isBigInt("1n");

Returns boolean true if the value is a primitive BigInt; false otherwise.

Meta

since: 1.0.0

isPrimitive

Determines whether the value is a primitive value.

Parameters

value any The value to check.

Examples

Primitive values

// returns true
isPrimitive(undefined);
isPrimitive(null);
isPrimitive(false);
isPrimitive(0);
isPrimitive("abc");
isPrimitive(Symbol("abc"));
isPrimitive(BigInt(1234567890));

Non-primitive values

// returns false
isPrimitive(new Number(1));
isPrimitive([1, 2, 3]);
isPrimitive(function () {});

Returns boolean true if the value is a primitive value; false otherwise.

Meta

since: 1.0.0

Utility

isNullish

See: undefined
See: null

Determines whether the value is null or undefined.

Parameters

value any The value to check.

Examples

Nullish values

// returns true
isNullish();
isNullish(undefined);
isNullish(void 0);

Non-nullish values

// returns false
isNullish(null);
isNullish(false);
isNullish(0);
isNullish("");
isNullish([]);
isNullish(NaN);

Returns boolean true if the value is null or undefined; false otherwise.

Meta

since: 1.0.0

isEmpty

Determines whether the value is an empty value which can be one of the following:

null
undefined
A string whose length is zero
An array with no elements
A plain object with no enumerable keys
An iterable with no iterable values

Parameters

value any The value to check.

Examples

Empty values

// returns true
isEmpty(null);
isEmpty(undefined);
isEmpty("");
isEmpty([]);
isEmpty({});
isEmpty(new Set());

Non-empty values

// returns false
isEmpty(" ");
isEmpty(0);
isEmpty(false);
isEmpty([null]);
isEmpty({a: ""});
isEmpty(NaN);

Returns boolean true if the value is an empty value; false otherwise.

Meta

since: 1.0.0

isBlank

Determines whether the value is a blank value which can be one of the following:

null
undefined
A string whose length is zero or has only space characters
An array that has no elements or has only nullish values
A plain object that has no enumerable keys or has only nullish values
An iterable that has no iterable values or has only nullish values.

Parameters

value any The value to check.

Examples

Blank values

// returns true
isBlank(null);
isBlank(undefined);
isBlank(" \t\n ");
isBlank([undefined, null]);
isBlank({a: null, b: undefined});
isBlank(new Set(null));

Non-blank values

// returns false
isBlank(0);
isBlank(false);
isBlank(" a ");
isBlank([""]);
isBlank({a: ""});
isBlank(NaN);

Returns boolean true if the value is a blank value; false otherwise.

Meta

since: 1.0.0

isTruthy

Determines whether the value is a truthy value. A truthy value is a value that is considered true when encountered in a Boolean context. All values are truthy except false, 0, "", undefined, null and NaN.

Parameters

value any The value to check.

Examples

Truthy values

// returns true
isTruthy(true);
isTruthy(1);
isTruthy("false");
isTruthy(new Boolean(false));
isTruthy({});

Non-truthy values

// returns false
isTruthy(false);
isTruthy(0);
isTruthy("");
isTruthy(undefined);
isTruthy(null);
isTruthy(NaN);

Returns boolean true if the value is a truthy value; false otherwise.

Meta

since: 1.0.0

isFalsy

Determines whether the value is a falsy value which can be one of the following:

false
0
""
undefined
null
NaN

Parameters

value any The value to check.

Examples

Falsy values

// returns true
isFalsy(false);
isFalsy(0);
isFalsy("");
isFalsy(undefined);
isFalsy(null);
isFalsy(NaN);

Non-falsy values

// returns false
isFalsy(true);
isFalsy(-1);
isFalsy("false");
isFalsy(new Boolean(false));
isFalsy({});

Returns boolean true if the value is a falsy value; false otherwise.

Meta

since: 1.0.0

isTypeOf

Determines whether the value has a specified type. Based on the type of the type value, it will check the following:

string - checks if the type matches (case-sensitive) using the typeof operator.
function - checks if the value is an instance of the function/class using the instanceof operator; if the test returns false, it checks if the function returns a truthy value when invoked with the value.
null/undefined - checks if the value is equal to the type using the strict equality (===) operator.
array - checks if the value has any type defined in the array.

Parameters

value any The value to check.
type (string | Function | null | undefined | Array) The expected type

Examples

Matching type values

// returns true
isTypeOf(1, "number");
isTypeOf({a: 1}, Object);
isTypeOf("abc", ["string", undefined]);

Non-matching type values

// returns false
isTypeOf(1, "boolean");
isTypeOf("", String);
isTypeOf(null, ["string", String]);

Returns boolean true if the value is of the type; false otherwise.

Meta

since: 1.0.0

Number

isInteger

Determines whether the value is an integer (a primitive number or Number object).

Parameters

value any The value to check.

Examples

Integer values

// returns true
isInteger(1);
isInteger(new Number(1));

Non-integer values

// returns false
isInteger(isInteger(0.1));
isInteger("1");
isInteger(Infinity);
isInteger(NaN);

Returns boolean true if the value is an integer; false otherwise.

Meta

since: 1.0.0

isFloat

Determines whether the value is a finite number with a decimal point (a primitive number or Number object).

Parameters

value any The value to check.

Examples

Float values

// returns true
isFloat(0.1);
isFloat(-1234.56789);
isFloat(new Number(0.1));

Non-float values

// returns false
isFloat(1);
isFloat(1.0);
isFloat("1.2");

Returns boolean true if the value is a finite number with a decimal point; false otherwise.

Meta

since: 1.0.0

isFinite

See: isFinite

Determines whether the value is a finite number (a primitive number or Number object).

Parameters

value any The value to check.

Examples

Finite values

// returns true
isFinite(0);
isFinite(-0.1);
isFinite(Number.MAX_VALUE);

Non-finite values

// returns false
isFinite(Infinity);
isFinite("1");
isFinite(NaN);

Returns boolean true if the value is a finite number; false otherwise.

Meta

since: 1.0.0

isInfinite

See: isFinite

Determines whether the value is a primitive number or Number object that represents positive or negative infinity.

Parameters

value any The value to check.

Examples

Infinite values

// returns true
isInfinite(Infinity);
isInfinite(Number.NEGATIVE_INFINITY);

Non-infinite values

// returns false
isInfinite(Number.MAX_VALUE);
isInfinite(NaN);

Returns boolean true if the value is a number that represents positive or negative infinity; false otherwise.

Meta

since: 1.0.0

isNaN

See: Number.isNaN

Determines whether the value is NaN (a primitive number or a Number object). NaN is the only value in javascript that is not equal to itself.

Parameters

value any The value to check.

Examples

NaN values

// returns true
isNaN(NaN);
isNaN(new Number(NaN));
isNaN(0/0);

Non-NaN values

// returns false
isNaN(undefined);
isNaN(null);
isNaN("NaN");
isNaN(Infinity);

Returns boolean true if the value is NaN; false otherwise.

Meta

since: 1.0.0

isNumeric

Determines whether the value is a numeric value which can be one of the following:

A primitive number or Number object that has a finite value
A primitive string or String object that represents a finite number
A BigInt

Parameters

value any The value to check.

Examples

Numeric values

// returns true
isNumeric(1);
isNumeric(new Number(1));
isNumeric("1.0");
isNumeric(new String("-1.234e+8"))
isNumeric(BigInt(1234567890));
isNumeric(Infinity);

Non-numeric values

// returns false
isNumeric(NaN);
isNumeric(Infinity);
isNumeric("12000n");
isNumeric("1*2");

Returns boolean true if the value is a numeric value; false otherwise.

Meta

since: 1.0.0

Object

isObject

Determines whether the value is an Object.

Parameters

value any The value to check.

Examples

Object values

// returns true
isObject({a: 1, b: 2});
isObject(["a", "b"]);
isObject(new Object());
isObject(new Number(1));
isObject(function() {});

Non-object values

// returns false
isObject(null);
isObject("abc");
isObject(Symbol("abc"));
isObject(1);
isObject(BigInt(1));

Returns boolean true if the value is an Object; false otherwise.

Meta

since: 1.0.0

isPlainObject

Determines whether the value is a plain object created using object literal or by the Object constructor.

Parameters

value any The value to check.

Examples

Plain object values

// returns true
isPlainObject({a: 1, b: 2});
isPlainObject(new Object());

Non-plain-object values

// returns false
isPlainObject(null);
isPlainObject("abc");
isPlainObject([1, 2]);
isPlainObject(new Number(1));

Returns boolean true if the value is a plain object; false otherwise.

Meta

since: 1.0.0

isCyclic

Determines whether the value is an cyclic object with a circular reference. A cycle object has an enumerable property (or a sub-property) whose value points to the object itself or a property of the object.

Parameters

value any The value to check.

Examples

Cyclic object

// returns true
var obj = {};
obj.ref = obj;

isCyclic(obj);

Non-cyclic values

// returns false
isCyclic({a: 1, b: 2});
isCyclic([1, 2, 3]);
isCyclic("abc");
isCyclic(function() {});

Returns boolean true if the value is a cyclic object with a circular reference; false otherwise.

Meta

since: 1.2.0

isIterable

See: Iterable

Determines whether the value is iterable which can be used in a for..of operator.

Parameters

value any The value to check.

Examples

Iterable values

// returns true
isIterable([1, 2, 3]);
isIterable("abc");
isIterable(new Map());
isIterable(new Set());
isIterable({[Symbol.iterator]: function() {}});

Non-iterable values

// returns false
isIterable({a: 1, b: 2});
isIterable(12345);

Returns boolean true if the value is iterable; false otherwise.

Meta

since: 1.0.0

isFunction

Determines whether the value is a Function object.

Parameters

value any The value to check.

Examples

Function values

// returns true
isFunction(function() {});
isFunction(Object);

Non-function values

// returns false
isFunction(null);
isFunction(new Object());
isFunction("function() {}");

Returns boolean true if the value is a Function object; false otherwise.

Meta

since: 1.0.0

isDate

See: Date

Determines whether the value is a Date object.

Parameters

value any The value to check.

Examples

Date values

// returns true
isDate(new Date());
isDate(new Date(""));

Non-date values

// returns false
isDate("2001-01-01T00:00:00.000Z");
isDate(978307200000);

Returns boolean true if the value is a Date object; false otherwise.

Meta

since: 1.0.0

isValidDate

See: Date

Determines whether the value is a valid Date object.

Parameters

value any The value to check.

Examples

Valid Date objects

// returns true
isValidDate(new Date());
isValidDate(new Date("2001-01-01T00:00:00.000Z"));
isValidDate(new Date(-1));

Invalid Date & non-date values

// returns false
isValidDate(new Date(""));
isValidDate("2001-01-01T00:00:00.000Z");
isValidDate(978307200000);

Returns boolean true if the value is a valid Date object; false otherwise.

Meta

since: 1.3.0

isInvalidDate

See: Date

Determines whether the value is an invalid Date object.

Parameters

value any The value to check.

Examples

Invalid Date objects

// returns true
isInvalidDate(new Date(""));
isInvalidDate(new Date(NaN));

Valid Date & non-date values

// returns false
isInvalidDate(new Date());
isInvalidDate("2001-01-01T00:00:00.000Z");
isInvalidDate(978307200000);

Returns boolean true if the value is an invalid Date object; false otherwise.

Meta

since: 1.3.0

isRegExp

See: RegExp

Determines whether the value is a RegExp object.

Parameters

value any The value to check.

Examples

RegExp values

// returns true
isRegExp(/[a-z]/);
isRegExp(new RegExp("[a-z]"));

Non-RegExp values

// returns false
isRegExp("[a-z]");
isRegExp("/[a-z]/");

Returns boolean true if the value is a RegExp object; false otherwise.

Meta

since: 1.0.0

isPromise

See: Promise

Determines whether the value is a Promise object.

Parameters

value any The value to check.

Examples

Promise values

// returns true
isPromise(new Promise(resolve, reject));
isPromise(Promise.resolve());
isPromise(Promise.reject());

Non-promise values

// returns false
isPromise({then: function() {}, catch: function() {}});

Returns boolean true if the value is a Promise object; false otherwise.

Meta

since: 1.0.0

isPromiseLike

See: Promise API Reference

Determines whether the value is an object that defines then and catch methods.

Parameters

value any The value to check.

Examples

Promise-like objects

// returns true
isPromiseLike(new Promise(resolve, reject));
isPromiseLike({then: function() {}, catch: function() {}});

Non-promise-like values

// returns false
isPromiseLike({then: function() {}});
isPromiseLike({then: true, catch: true});

Returns boolean true if the value is a Promise-like object; false otherwise.

Meta

since: 1.0.0

isThenable

Determines whether the value is an object that defines a then method.

Parameters

value any The value to check.

Examples

Thenable objects

// returns true
isThenable(new Promise(resolve, reject));
isThenable({then: function() {}});

Non-thenable values

// returns false
isThenable(null);
isThenable({then: true});

Returns boolean true if the value is a thenable object; false otherwise.

Meta

since: 1.1.0

isError

See: Error

Determines whether the value is an Error object.

Parameters

value any The value to check.

Examples

Error objects

// returns true
isError(new Error("Validation error"));
isError(new TypeError("Expected a number, but found: " + value));

Non-Error values

// returns false
isError(null);
isError(NaN);
isError(Promise.reject());
isError({name: "TypeError", message: "Expected a number"});

Returns boolean true if the value is an Error object; false otherwise.

Meta

since: 1.0.0

Array

isArray

Determines whether the value is an Array object.

Parameters

value any The value to check.

Examples

Array values

// returns true
isArray(["a", "b"]);
isArray(new Array());

Non-array values

// returns false
isArray("abc");
isArray({length: 0});
isArray(new Int8Array());

Returns boolean true if the value is an Array object; false otherwise.

Meta

since: 1.0.0

isArrayOf

Determines whether the value is a non-empty array and all elements in the array have the specified type.

Parameters

value any The value to check.
type (string | Function | null | undefined | Array) The type of elements

Examples

Matching values

// returns true
isArrayOf([1, 2, 3], "number");
isArrayOf(["a", "b", null], ["string", null]);
isArrayOf([{a: 1}, {b: 2}], Object);

Non-matching values

// returns false
isArrayOf([1, 2, "c"], "number");
isArrayOf([], undefined);

Returns boolean true if the value is a non-empty array and and all elements in the array have the specified type; false otherwise.

Meta

since: 1.1.0

isArrayLike

Determines whether the value is an array-like object with a "length" property whose value is an integer and is within 0 ~ Number.MAX_SAFE_INTEGER (both inclusive).

Parameters

value any The value to check.

Examples

Array-like objects

// returns true
isArrayLike([]);
isArrayLike("abc");
isArrayLike({length: 0});
isArrayLike(new Int8Array());

Non-array-like values

// returns false
isArrayLike({});
isArrayLike({length: -1})
isArrayLike(new Set());
isArrayLike(Array);

Returns boolean true if the value is an array-like object; false otherwise.

Meta

since: 1.0.0

isArrayLikeOf

Determines whether the value is a non-empty array-like object and all elements in the object have the specified type.

Parameters

value any The value to check.
type (string | Function | null | undefined | Array) The type of elements

Examples

Matching values

// returns true
isArrayLikeOf([1, 2, 3], "number");
isArrayLikeOf({0: "a", 1: "b", length: 2}, "string");

Non-matching values

// returns false
isArrayLikeOf([1, 2, "c"], "number");
isArrayLikeOf({a: 1, b: 2, length: 2}, "number");

Returns boolean true if the value is a non-empty array-like object and all elements in the object have the specified type; false otherwise.

Meta

since: 1.1.0

isPair

Determines whether the value is an array with two elements.

Parameters

value any The value to check.

Examples

Pair values

// returns true
isPair([1, 2]);
isPair([null, {}]);

Non-pair values

// returns false
isPair([]);
isPair({a: 1, b: 2});
isPair("ab");

Returns boolean true if the value is an array with two elements; false otherwise.

Meta

since: 1.2.0

Collection

isMap

See: Map

Determines whether the value is a Map object.

Parameters

value any The value to check.

Examples

Map values

// returns true
isMap(new Map());

Non-Map values

// returns false
isMap(new WeakMap());
isMap({a: 1, b: 2});

Returns boolean true if the value is a Map object; false otherwise.

Meta

since: 1.0.0

isSet

See: Set

Determines whether the value is a Set object.

Parameters

value any The value to check.

Examples

Set values

// returns true
isSet(new Set());

Non-Set values

// returns false
isSet(new WeakSet());
isSet([1, 2, 3]);

Returns boolean true if the value is a Set object; false otherwise.

Meta

since: 1.0.0

isWeakMap

See: WeakMap

Determines whether the value is a WeakMap object.

Parameters

value any The value to check.

Examples

WeakMap values

// returns true
isWeakMap(new WeakMap());

Non-WeakMap values

// returns false
isWeakMap(new Map());
isWeakMap({a: 1, b: 2});

Returns boolean true if the value is a WeakMap object; false otherwise.

Meta

since: 1.0.0

isWeakSet

See: WeakSet

Determines whether the value is a WeakSet object.

Parameters

value any The value to check.

Examples

WeakSet values

// returns true
isWeakSet(new WeakSet());

Non-WeakSet values

// returns false
isWeakSet(new Set());
isWeakSet([1, 2, 3]);

Returns boolean true if the value is a WeakSet object; false otherwise.

Meta

since: 1.0.0

Node

isNode

See: Node

Determines whether the value is a DOM Node object.

Parameters

value any The value to check.

Examples

Node objects

// returns true
isNode(document);
isNode(document.createElement("div"));
isNode(new DocumentFragment());

Non-Node values

// returns false
isNode(Node);
isNode(window);

Returns boolean true if the value is a DOM Node object; false otherwise.

Meta

since: 1.1.0

isElement

See: Element

Determines whether the value is a DOM Element object.

Parameters

value any The value to check.

Examples

Element objects

// returns true
isElement(document.createElement("div"));

Non-Element values

// returns false
isElement(document);
isElement(window);
isElement(new DocumentFragment());

Returns boolean true if the value is a DOM Element object; false otherwise.

Meta

since: 1.1.0

isFragment

See: DocumentFragment

Determines whether the value is a DocumentFragment object.

Parameters

value any The value to check.

Examples

DocumentFragment objects

// returns true
isFragment(new DocumentFragment());

Non-DocumentFragment values

// returns false
isFragment(document);
isFragment(window);
isFragment(document.createElement("div"));

Returns boolean true if the value is a DocumentFragment object; false otherwise.

Meta

since: 1.1.0

type checking type-checking types primitives objects

@infinitebrahmanuniverse/nolb-go-@everything-registry/sub-chunk-1774 go-expect

2 years ago

2 years ago

2 years ago

2 years ago

2 years ago

Go Types

Installation

Usage

ES6

Node

Web browser

Documentation

Table of Contents

Primitive

isUndefined

Parameters

Examples

isNull

Parameters

Examples

isBoolean

Parameters

Examples

isNumber

Parameters

Examples

isString

Parameters

Examples

isSymbol

Parameters

Examples

isBigInt

Parameters

Examples

isPrimitive

Parameters

Examples

Utility

isNullish

Parameters

Examples

isEmpty

Parameters

Examples

isBlank

Parameters

Examples

isTruthy

Parameters

Examples

isFalsy

Parameters

Examples

isTypeOf

Parameters

Examples

Number

isInteger

Parameters

Examples

isFloat

Parameters

Examples

isFinite

Parameters

Examples

isInfinite

Parameters

Examples

isNaN

Parameters

Examples

isNumeric

Parameters

Examples

Object

isObject

Parameters

Examples

isPlainObject

Parameters

Examples

isCyclic

Parameters