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update readme, add .of() (untested)
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‎README.md‎

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---
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## Type Names
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This module uses an expanded set of type names that make no distinction between primitive values and objects.
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For example, `5` and `new Number(5)` are both of type "number".
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| Type Name | Primitive Values | Instances Of Classes
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| - | - | -
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| defined | any value (not undefined) | `Object`
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| **undefined** | undefined |
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| primitive | not an instance of `Object` |
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| **object** | | `Object`
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| objectish | `null` | `Object`
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| **null** | `null` |
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| nullish | undefined, `null` |
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| **boolean** | `false`, `true` |
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| false | `false` |
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| true | `true` |
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| falsy | undefined, `null`, `false`, `0n`, `NaN`, `0`, `""` |
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| truthy | values that are not _falsy_ | `Object`
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| **symbol** | a `Symbol` |
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| **bigint** | `0n`, `5n` |
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| numberish | `0`, `5`, `Infinity`, `NaN` | `Number`
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| **nan** | `NaN` | `Number` instances with value `NaN`
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| **number** | `0`, `5`, `Infinity` | `Number` excluding instances with value `NaN`
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| real | `0`, `5` | `Number` instances for real numbers
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| infinite | `Infinity` | `Number` instances for infinite numbers
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| **string** | `""`, `"foo"` | `String`
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| **array** | `[]`, `[1,2]` | `Array`
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| **map** | | `Map`
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| **set** | | `Set`
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| **weakmap** | | `WeakMap`
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| **weakset** | | `WeakSet`
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| empty | `[]` | `String` or `Array` of length == 0, `Map` or `Set` of size == 0
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| nonempty | values that are not _empty_ | instances that are not _empty_
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| **date** | | `Date`
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| **error** | | `Error`
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| **function** | | `Function`, `function(){}`, `()=>{}`
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| **promise** | | `Promise`
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| **regex** | | `Regex`, `/foo/`
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## Determine a Type
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The **is()** function returns an object describing the type of its argument.
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This module uses an expanded set of type names and related descriptors to simplify common tests of values.
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Basic types do not distinguish between primitives and objects, but descriptors _primitive_ or _object_
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can be used to determine that aspect.
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For example, `5` and `new Number(5)` are both _number_, but `5` is _primitive_ and `new Number(5)` is _object_.
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Syntax:
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> **is**(_value_)
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Returned object:
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| Property | Description
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| - | -
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| .**type** | The type name used by this module.
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| .**typeof** | The value returned by the `typeof` operator.
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| .**toStringTag** | The name used by `Object.prototype.toString()`. `undefined` for primitives.
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| .**constructorName** | The name of the argument's constructor. `undefined` for primitives.
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| .**isObject** | True if the value is an object.
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| .**isPrimitive** | True if the value is a primitive.
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## Type Testing
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Each of the type-testing methods return a boolean indicating if the argument is of that type.
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The **is()** function returns an **IsType** object describing its argument.
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Syntax:
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> is._typeTester_(_value_)
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### Basics
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| Method | Tests for
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| - | -
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| is.**function**() | instance of `Function`
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| is.**object**() | instance of `Object`
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| is.**primitive**() | primitives
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| is.**null**() | `null`
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| is.**nullish**() | `undefined`, `null`
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| is.**undefined**() | `undefined`
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| is.**defined**() | not `undefined`
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### Booleans
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> **is**(_value_)
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| Method | Tests for
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| - | -
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| is.**boolean**() | `false`, `true`, instance of `Boolean`
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| is.**falsy**() | `false`, `undefined`, `null`, `NaN`, `0`, `-0`, `0n`, `""`, [`document.all`](https://developer.mozilla.org/en-US/docs/Web/API/Document/all#conversion_to_boolean)
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| is.**truthy**() | not falsy
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### Numbers
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## IsType Object
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| Method | Tests for
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| Member | Description
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| - | -
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| is.**bigint**() | _bigint_ primitive
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| is.**date**() | instance of `Date`
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| is.**numberish**() | _number_ primitive, instance of `Number`
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_Numberish_ values can be more explicitly tested using the following methods:
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| .type | The type of _value_ (using this module's type names).
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| .of(_class_) | Tests if _value_ was an instance of _class_.
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| .all(_...descriptors)_ | Takes a list of descriptor names as arguments. Returns `true` if **all** of them applied to _value_.
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| .any(_...descriptors_) | Takes a list of descriptor names as arguments. Returns `true` if **any** of them applied to _value_.
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| \[[_descriptor_](#type-names-and-related-descriptors)\] | Descriptors are listed in the table below. Each descriptor property is a boolean that is `true` if it applied to _value_.
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Enumerable properties of the **is** function are string values of the name of each descriptor. These can be used
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in the `.all()` and `.any()` methods instead of string literals.
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For example, `is(_value_).all("number", "object")` is equivalent to `is(_value_).all(is.number, is.object)`.
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## Type Names and Related Descriptors
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| Descriptor | Type Name | Primitive Values | Instances Of Classes
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| - | - | - | -
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| defined | | not undefined | `Object`
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| **undefined** | yes | undefined |
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| primitive | | not an instance of `Object` |
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| **object** | yes | | `Object`
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| objectish | | `null` | `Object`
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| **null** | yes | `null` |
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| nullish | | undefined, `null` |
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| **boolean** | yes | `false`, `true` |
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| false | | `false` |
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| true | | `true` |
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| falsy | | undefined, `null`, `false`, `0n`, `NaN`, `0`, `""` |
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| truthy | | not _falsy_ | `Object`
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| **symbol** | yes | a `Symbol` |
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| **bigint** | yes | `0n`, `5n` |
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| numberish | | `0`, `5`, `Infinity`, `NaN` | `Number`
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| **nan** | yes | `NaN` | `Number` with value `NaN`
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| **number** | yes | `0`, `5`, `Infinity` | `Number` excluding those with value `NaN`
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| real | | `0`, `5` | `Number` with a real number value
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| infinite | | `Infinity` | `Number` with an infinite value
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| **string** | yes | `""`, `"foo"` | `String`
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| **array** | yes | `[]`, `[1,2]` | `Array`
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| **map** | yes | | `Map`
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| **set** | yes | | `Set`
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| **weakmap** | yes | | `WeakMap`
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| **weakset** | yes | | `WeakSet`
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| empty | | `""`, `[]` | `String` or `Array` of length == 0, `Map` or `Set` of size == 0
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| nonempty | | not _empty_ | `String`, `Array`, `Map`, or `Set` that is not _empty_
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| **date** | yes | | `Date`
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| **error** | yes | | `Error`
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| **function** | yes | | `Function`, `function(){}`, `()=>{}`
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| **promise** | yes | | `Promise`
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| **regex** | yes | | `Regex`, `/foo/`
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| Method | Tests for
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| - | -
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| is.**real**() | real numbers
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| is.**infinite**() | `Infinity`, `-Infinity`
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| is.**number**() | real numbers, `Infinity`, `-Infinity`
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| is.**nan**() | `NaN`
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Note that JavaScript doesn't always treat mathematical expressions of undefined or indeterminate form as you might expect. For example, `1/0` is an undefined form, but JavaScript evaluates it as `Infinity`.
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### Text
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| Method | Tests for
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| - | -
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| is.**regex**() | instance of `RegExp`
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| is.**string**() | _string_ primitive, instance of `String`
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### Collections
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| Method | Tests for
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| - | -
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| is.**array**() | instance of `Array`
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| is.**map**() | instance of `Map`
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| is.**set**() | instance of `Set`
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| is.**weakmap**() | instance of `WeakMap`
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| is.**weakset**() | instance of `WeakSet`
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### Other Common Types
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| Method | Tests for
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| - | -
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| is.**error**() | instance of `Error`
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| is.**promise**() | instance of `Promise`
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| is.**symbol**() | _symbol_ primitive
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## Additional Methods
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| Method | Description
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| - | -
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| is.**empty**(_value_) | Tests for an empty _string_ primitive or if an object's `.length` or `.size` property equals zero.
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| is.**of**(_value_, _class_) | Tests if _value_ is an instance of _class_. (Same as using the `instanceof` operator.)

‎isType.mjs.js‎

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}
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}
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class Is extends TypeTest {
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class IsType extends TypeTest {
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#valueConstructor;
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constructor(value){
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super(value);
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if(value instanceof Object) this.#valueConstructor = value.constructor;
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}
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get type(){
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return this.toString();
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}
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of(constructor){
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return this.#valueConstructor && (this.#valueConstructor === constructor || this.#valueConstructor.prototype instanceof constructor);
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}
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all(...propNames){
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return propNames.every(propName=>this[propName]);
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}
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/**
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* Determine the type of a value. The returned object includes boolean properties to quickly test against specific types or for specific states (e.g., 'empty').
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* @param {*} value - The value to be tested.
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* @returns {Is}
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* @returns {IsType}
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*/
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function is(value){
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return new Is(value);
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return new IsType(value);
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}
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for(const propName in new TypeTest()){
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is[propName] = propName;
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Object.defineProperty(is, propName, {
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value: propName,
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enumerable: true,
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});
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}
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export { is as default };

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