@xylabs/typeof
Advanced tools
Base functionality used throughout XY Labs TypeScript/JavaScript libraries
Base functionality used throughout XY Labs TypeScript/JavaScript libraries
@xylabs/typeof
| Type Alias | Description |
|---|---|
| Brand | Creates a branded type by intersecting base type T with brand type B, enabling nominal typing in TypeScript. |
| IdentityFunction | A type guard function that narrows an unknown value to type T. |
| FieldType | Union of string literals representing the possible types of an object field. |
| ObjectTypeShape | Describes the expected shape of an object by mapping each key to its expected field type. |
| TypeOfTypes | Union of string literals representing the possible results of the extended typeOf function. |
| TypedValue | A value that can appear in a typed object tree (primitives, objects, arrays, functions, and symbols). |
| TypedKey | A valid key for a typed object. Defaults to string |
| TypedObject | An object whose keys are TypedKey and whose values are TypedValue. |
| TypedArray | An array of TypedValue elements. |
| AnyFunction | A function type that accepts any arguments and returns unknown. |
| RecordKey | A union of valid object key types. |
| Function | Description |
|---|---|
| isTypedKey | Type guard that checks whether a value is a valid TypedKey (string, bigint, number, or symbol). |
| isTypedValue | Type guard that checks whether a value is a valid TypedValue. |
| isTypedArray | Type guard that checks whether a value is a TypedArray (an array where every element is a TypedValue). |
| isValidTypedFieldPair | Type guard that checks whether a key-value pair has a valid TypedKey and TypedValue. |
| isTypedObject | Type guard that checks whether a value is a TypedObject (an object with TypedKey keys and TypedValue values). |
| ifDefined | Invokes the callback only if the value is neither null nor undefined. |
| ifTypeOf | Invokes the callback if the value matches the specified type, with an optional additional predicate. |
| isUndefined | Type guard that checks whether a value is undefined. |
| isDefined | Type guard that checks whether a value is not undefined. |
| isNull | Type guard that checks whether a value is null. |
| isDefinedNotNull | Type guard that checks whether a value is neither undefined nor null. |
| isUndefinedOrNull | Type guard that checks whether a value is undefined or null. |
| isBigInt | Type guard that checks whether a value is a bigint. |
| isString | Type guard that checks whether a value is a string. |
| isNumber | Type guard that checks whether a value is a number. |
| isObject | Type guard that checks whether a value is a plain object (not null and not an array). |
| isArray | Type guard that checks whether a value is an array. |
| isFunction | Type guard that checks whether a value is a function. |
| isSymbol | Type guard that checks whether a value is a symbol. |
| isEmptyObject | Type guard that checks whether a value is an object with no own keys. |
| isEmptyString | Type guard that checks whether a value is an empty string. |
| isEmptyArray | Type guard that checks whether a value is an empty array. |
| isPopulatedArray | Type guard that checks whether a value is a non-empty array. |
| isEmpty | Type guard that checks whether a value is empty (empty string, empty array, or empty object). |
| isFalsy | Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n). |
| isTruthy | Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n). |
| isBoolean | Type guard that checks whether a value is a boolean. |
| isDateString | Type guard that checks whether a value is a string that can be parsed as a valid date. |
| isDate | Type guard that checks whether a value is a Date instance. |
| isRegExp | Type guard that checks whether a value is a RegExp instance. |
| isError | Type guard that checks whether a value is an Error instance. |
| isPromise | Type guard that checks whether a value is a Promise instance. |
| isPromiseLike | Type guard that checks whether a value is promise-like (has a then method). |
| isMap | Type guard that checks whether a value is a Map instance. |
| isArrayBufferView | Type guard that checks whether a value is an ArrayBufferView (e.g., TypedArray or DataView). |
| isSet | Type guard that checks whether a value is a Set instance. |
| isWeakMap | Type guard that checks whether a value is a WeakMap instance. |
| isWeakSet | Type guard that checks whether a value is a WeakSet instance. |
| isDataView | Type guard that checks whether a value is a DataView instance. |
| isBlob | Type guard that checks whether a value is a Blob instance. |
| isFile | Type guard that checks whether a value is a File instance. |
| isType | Checks whether a value matches the expected field type, with correct handling for arrays and nulls. |
| typeOf | Extended typeof that distinguishes arrays from objects (unlike native typeof). |
| validateType | Validates that a value matches the expected type, returning the value and any errors. |
function ifDefined<T>(value: T, func: (value: T) => void): T | undefined;
Invokes the callback only if the value is neither null nor undefined.
| Type Parameter |
|---|
T |
| Parameter | Type | Description |
|---|---|---|
value | T | The value to check. |
func | (value: T) => void | The callback to invoke with the value if it is defined. |
T | undefined
The value if defined, or undefined otherwise.
function ifTypeOf<T, R>(
typeName: TypeOfTypes,
value: unknown,
trueFunc: (value: T) => R,
isFunc?: (value: T) => boolean): R | undefined;
Invokes the callback if the value matches the specified type, with an optional additional predicate.
| Type Parameter |
|---|
T |
R |
| Parameter | Type | Description |
|---|---|---|
typeName | TypeOfTypes | The expected type name to match against. |
value | unknown | The value to check. |
trueFunc | (value: T) => R | The callback to invoke if the type matches. |
isFunc? | (value: T) => boolean | Optional additional predicate that must also return true. |
R | undefined
The result of trueFunc if the type matches (and isFunc passes), or undefined.
function isArray(value: unknown): value is readonly unknown[];
Type guard that checks whether a value is an array.
| Parameter | Type |
|---|---|
value | unknown |
value is readonly unknown[]
function isArray<T>(value: T): value is Extract<T, readonly unknown[]>;
Type guard that checks whether a value is an array.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, readonly unknown[]>
function isArrayBufferView(value: unknown): value is ArrayBufferView<ArrayBufferLike>;
Type guard that checks whether a value is an ArrayBufferView (e.g., TypedArray or DataView).
| Parameter | Type |
|---|---|
value | unknown |
value is ArrayBufferView<ArrayBufferLike>
function isArrayBufferView<T>(value: T): value is Extract<T, ArrayBufferView<ArrayBufferLike>>;
Type guard that checks whether a value is an ArrayBufferView (e.g., TypedArray or DataView).
| Type Parameter |
|---|
T extends ArrayBufferView<ArrayBufferLike> |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, ArrayBufferView<ArrayBufferLike>>
function isBigInt(value: unknown): value is bigint;
Type guard that checks whether a value is a bigint.
| Parameter | Type |
|---|---|
value | unknown |
value is bigint
function isBigInt<T>(value: T): value is Extract<T, bigint>;
Type guard that checks whether a value is a bigint.
| Type Parameter |
|---|
T extends bigint |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, bigint>
function isBlob(value: unknown): value is Blob;
Type guard that checks whether a value is a Blob instance.
| Parameter | Type |
|---|---|
value | unknown |
value is Blob
function isBlob<T>(value: T): value is Extract<T, Blob>;
Type guard that checks whether a value is a Blob instance.
| Type Parameter |
|---|
T extends Blob |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Blob>
function isBoolean(value: unknown): value is boolean;
Type guard that checks whether a value is a boolean.
| Parameter | Type |
|---|---|
value | unknown |
value is boolean
function isBoolean<T>(value: T): value is Extract<T, boolean>;
Type guard that checks whether a value is a boolean.
| Type Parameter |
|---|
T extends boolean |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, boolean>
function isDataView(value: unknown): value is DataView<ArrayBufferLike>;
Type guard that checks whether a value is a DataView instance.
| Parameter | Type |
|---|---|
value | unknown |
value is DataView<ArrayBufferLike>
function isDataView<T>(value: T): value is Extract<T, DataView<ArrayBufferLike>>;
Type guard that checks whether a value is a DataView instance.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, DataView<ArrayBufferLike>>
function isDate(value: unknown): value is Date;
Type guard that checks whether a value is a Date instance.
| Parameter | Type |
|---|---|
value | unknown |
value is Date
function isDate<T>(value: T): value is Extract<T, Date>;
Type guard that checks whether a value is a Date instance.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Date>
function isDateString(value: unknown): value is string;
Type guard that checks whether a value is a string that can be parsed as a valid date.
| Parameter | Type |
|---|---|
value | unknown |
value is string
function isDateString<T>(value: T): value is Extract<T, string>;
Type guard that checks whether a value is a string that can be parsed as a valid date.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, string>
function isDefined<T>(value: T): value is Exclude<T, undefined>;
Type guard that checks whether a value is not undefined.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Exclude<T, undefined>
function isDefinedNotNull<T>(value: T): value is Exclude<T, null | undefined>;
Type guard that checks whether a value is neither undefined nor null.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Exclude<T, null | undefined>
function isEmpty<T>(value: unknown): value is T;
Type guard that checks whether a value is empty (empty string, empty array, or empty object).
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | unknown |
value is T
function isEmpty<K, V, T>(value: T): value is Extract<T, Record<K, never>>;
Type guard that checks whether a value is empty (empty string, empty array, or empty object).
| Type Parameter |
|---|
K extends RecordKey |
V |
T extends Record<K, V> |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Record<K, never>>
function isEmpty<T>(value: T): value is Extract<T, never[]>;
Type guard that checks whether a value is empty (empty string, empty array, or empty object).
| Type Parameter |
|---|
T extends unknown[] |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, never[]>
function isEmptyArray(value: unknown): value is [];
Type guard that checks whether a value is an empty array.
| Parameter | Type |
|---|---|
value | unknown |
value is []
function isEmptyArray<T>(value: T): value is Extract<T, unknown[]>;
Type guard that checks whether a value is an empty array.
| Type Parameter |
|---|
T extends unknown[] |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, unknown[]>
function isEmptyObject(value: unknown): value is {};
Type guard that checks whether a value is an object with no own keys.
| Parameter | Type |
|---|---|
value | unknown |
value is {}
function isEmptyObject<K, V, T>(value: T): value is Extract<T, Record<K, never>>;
Type guard that checks whether a value is an object with no own keys.
| Type Parameter |
|---|
K extends RecordKey |
V |
T extends Record<K, V> |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Record<K, never>>
function isEmptyString(value: unknown): value is "";
Type guard that checks whether a value is an empty string.
| Parameter | Type |
|---|---|
value | unknown |
value is ""
function isEmptyString<T>(value: T): value is Extract<T, "">;
Type guard that checks whether a value is an empty string.
| Type Parameter |
|---|
T extends string |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, "">
function isError(value: unknown): value is Error;
Type guard that checks whether a value is an Error instance.
| Parameter | Type |
|---|---|
value | unknown |
value is Error
function isError<T>(value: T): value is Extract<T, Error>;
Type guard that checks whether a value is an Error instance.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Error>
function isFalsy<T>(value: T): value is Extract<T, false | "" | 0 | 0n | null | undefined>;
Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, false | "" | 0 | 0n | null | undefined>
function isFalsy<T>(value: T): value is Extract<T, false>;
Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends boolean |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, false>
function isFalsy<T>(value: T): value is Extract<T, 0>;
Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends number |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, 0>
function isFalsy<T>(value: T): value is Extract<T, 0n>;
Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends bigint |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, 0n>
function isFalsy<T>(value: T): value is Extract<T, null>;
Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends null |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, null>
function isFalsy<T>(value: T): value is Extract<T, undefined>;
Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends undefined |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, undefined>
function isFalsy<T>(value: T): value is Extract<T, "">;
Type guard that checks whether a value is falsy (0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends string |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, "">
function isFile(value: unknown): value is File;
Type guard that checks whether a value is a File instance.
| Parameter | Type |
|---|---|
value | unknown |
value is File
function isFile<T>(value: T): value is Extract<T, File>;
Type guard that checks whether a value is a File instance.
| Type Parameter |
|---|
T extends File |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, File>
function isFunction(value: unknown): value is AnyFunction;
Type guard that checks whether a value is a function.
| Parameter | Type |
|---|---|
value | unknown |
value is AnyFunction
function isFunction<T>(value: T): value is Extract<T, AnyFunction>;
Type guard that checks whether a value is a function.
| Type Parameter |
|---|
T extends AnyFunction |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, AnyFunction>
function isMap(value: unknown): value is Map<unknown, unknown>;
Type guard that checks whether a value is a Map instance.
| Parameter | Type |
|---|---|
value | unknown |
value is Map<unknown, unknown>
function isMap<K, V, T>(value: T): value is Extract<T, Map<K, V>>;
Type guard that checks whether a value is a Map instance.
| Type Parameter |
|---|
K |
V |
T extends Map<K, V> |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Map<K, V>>
function isNull(value: unknown): value is null;
Type guard that checks whether a value is null.
| Parameter | Type |
|---|---|
value | unknown |
value is null
function isNull<T>(value: T): value is Extract<T, null>;
Type guard that checks whether a value is null.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, null>
function isNumber(value: unknown): value is number;
Type guard that checks whether a value is a number.
| Parameter | Type |
|---|---|
value | unknown |
value is number
function isNumber<T>(value: T): value is Extract<T, number>;
Type guard that checks whether a value is a number.
| Type Parameter |
|---|
T extends number |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, number>
function isObject(value: unknown): value is object;
Type guard that checks whether a value is a plain object (not null and not an array).
| Parameter | Type |
|---|---|
value | unknown |
value is object
function isObject<T>(value: T): value is Extract<T, object>;
Type guard that checks whether a value is a plain object (not null and not an array).
| Type Parameter |
|---|
T extends object |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, object>
function isPopulatedArray(value: unknown): value is readonly unknown[];
Type guard that checks whether a value is a non-empty array.
| Parameter | Type |
|---|---|
value | unknown |
value is readonly unknown[]
function isPopulatedArray<T>(value: T): value is Extract<T, readonly unknown[]>;
Type guard that checks whether a value is a non-empty array.
| Type Parameter |
|---|
T extends unknown[] |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, readonly unknown[]>
function isPromise(value: unknown): value is Promise<unknown>;
Type guard that checks whether a value is a Promise instance.
| Parameter | Type |
|---|---|
value | unknown |
value is Promise<unknown>
function isPromise<T>(value: T): value is Extract<T, Promise<unknown>>;
Type guard that checks whether a value is a Promise instance.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Promise<unknown>>
function isPromiseLike(value: unknown): value is Promise<unknown>;
Type guard that checks whether a value is promise-like (has a then method).
| Parameter | Type |
|---|---|
value | unknown |
value is Promise<unknown>
function isPromiseLike<T>(value: T): value is Extract<T, Promise<unknown>>;
Type guard that checks whether a value is promise-like (has a then method).
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, Promise<unknown>>
function isRegExp(value: unknown): value is RegExp;
Type guard that checks whether a value is a RegExp instance.
| Parameter | Type |
|---|---|
value | unknown |
value is RegExp
function isRegExp<T>(value: T): value is Extract<T, RegExp>;
Type guard that checks whether a value is a RegExp instance.
| Type Parameter |
|---|
T extends RegExp |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, RegExp>
function isSet(value: unknown): value is Set<unknown>;
Type guard that checks whether a value is a Set instance.
| Parameter | Type |
|---|---|
value | unknown |
value is Set<unknown>
function isSet<T>(value: unknown): value is Extract<T, Set<unknown>>;
Type guard that checks whether a value is a Set instance.
| Type Parameter |
|---|
T extends Set<unknown> |
| Parameter | Type |
|---|---|
value | unknown |
value is Extract<T, Set<unknown>>
function isString(value: unknown): value is string;
Type guard that checks whether a value is a string.
| Parameter | Type |
|---|---|
value | unknown |
value is string
function isString<T>(value: T): value is Extract<T, string>;
Type guard that checks whether a value is a string.
| Type Parameter |
|---|
T extends string |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, string>
function isSymbol(value: unknown): value is symbol;
Type guard that checks whether a value is a symbol.
| Parameter | Type |
|---|---|
value | unknown |
value is symbol
function isSymbol<T>(value: T): value is Extract<T, symbol>;
Type guard that checks whether a value is a symbol.
| Type Parameter |
|---|
T extends symbol |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, symbol>
function isTruthy<T>(value: T): value is Exclude<T, false | "" | 0 | 0n | null | undefined>;
Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Exclude<T, false | "" | 0 | 0n | null | undefined>
function isTruthy<T>(value: T): value is Extract<T, true>;
Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends boolean |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, true>
function isTruthy<T>(value: T): value is Extract<T, number>;
Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends number |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, number>
function isTruthy<T>(value: T): value is Extract<T, bigint>;
Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends bigint |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, bigint>
function isTruthy<T>(value: T): value is Extract<T, null>;
Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends null |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, null>
function isTruthy<T>(value: T): value is Extract<T, undefined>;
Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends undefined |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, undefined>
function isTruthy<T>(value: T): value is Extract<T, string>;
Type guard that checks whether a value is truthy (not 0, null, undefined, false, '', or 0n).
| Type Parameter |
|---|
T extends string |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, string>
function isType(value: unknown, expectedType: FieldType): boolean;
Checks whether a value matches the expected field type, with correct handling for arrays and nulls.
| Parameter | Type | Description |
|---|---|---|
value | unknown | The value to check. |
expectedType | FieldType | The expected type string. |
boolean
True if the value matches the expected type.
function isTypedArray(value: unknown): value is TypedArray;
Type guard that checks whether a value is a TypedArray (an array where every element is a TypedValue).
| Parameter | Type | Description |
|---|---|---|
value | unknown | The value to check. |
value is TypedArray
True if the value is an array of TypedValue elements.
function isTypedKey(value: unknown): value is string | number | symbol;
Type guard that checks whether a value is a valid TypedKey (string, bigint, number, or symbol).
| Parameter | Type | Description |
|---|---|---|
value | unknown | The value to check. |
value is string | number | symbol
True if the value is a valid TypedKey.
function isTypedObject(value: unknown): value is TypedObject;
Type guard that checks whether a value is a TypedObject (an object with TypedKey keys and TypedValue values).
| Parameter | Type | Description |
|---|---|---|
value | unknown | The value to check. |
value is TypedObject
True if the value is a valid TypedObject.
function isTypedValue(value: unknown): value is TypedValue;
Type guard that checks whether a value is a valid TypedValue.
| Parameter | Type | Description |
|---|---|---|
value | unknown | The value to check. |
value is TypedValue
True if the value is a string, number, boolean, null, TypedObject, or TypedArray.
function isUndefined(value: unknown): value is undefined;
Type guard that checks whether a value is undefined.
| Parameter | Type |
|---|---|
value | unknown |
value is undefined
function isUndefined<T>(value: T): value is Extract<T, undefined>;
Type guard that checks whether a value is undefined.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, undefined>
function isUndefinedOrNull(value: unknown): value is null | undefined;
Type guard that checks whether a value is undefined or null.
| Parameter | Type |
|---|---|
value | unknown |
value is null | undefined
function isUndefinedOrNull<T>(value: T): value is Extract<T, null | undefined>;
Type guard that checks whether a value is undefined or null.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, null | undefined>
function isValidTypedFieldPair(pair: [unknown, unknown]): pair is [key: string | number | symbol, value: TypedValue];
Type guard that checks whether a key-value pair has a valid TypedKey and TypedValue.
| Parameter | Type | Description |
|---|---|---|
pair | [unknown, unknown] | A tuple of [key, value] to validate. |
pair is [key: string | number | symbol, value: TypedValue]
True if the key is a TypedKey and the value is a TypedValue.
function isWeakMap(value: unknown): value is WeakMap<WeakKey, unknown>;
Type guard that checks whether a value is a WeakMap instance.
| Parameter | Type |
|---|---|
value | unknown |
value is WeakMap<WeakKey, unknown>
function isWeakMap<K, V, T>(value: T): value is Extract<T, WeakMap<K, V>>;
Type guard that checks whether a value is a WeakMap instance.
| Type Parameter |
|---|
K extends WeakKey |
V |
T extends WeakMap<K, V> |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, WeakMap<K, V>>
function isWeakSet(value: unknown): value is WeakSet<WeakKey>;
Type guard that checks whether a value is a WeakSet instance.
| Parameter | Type |
|---|---|
value | unknown |
value is WeakSet<WeakKey>
function isWeakSet<K, T>(value: T): value is Extract<T, WeakSet<K>>;
Type guard that checks whether a value is a WeakSet instance.
| Type Parameter |
|---|
K extends WeakKey |
T extends WeakSet<K> |
| Parameter | Type |
|---|---|
value | T |
value is Extract<T, WeakSet<K>>
function typeOf<T>(item: T): TypeOfTypes;
Extended typeof that distinguishes arrays from objects (unlike native typeof).
| Type Parameter |
|---|
T |
| Parameter | Type | Description |
|---|---|---|
item | T | The value to check. |
The type of the item as a TypeOfTypes string.
function validateType<T>(
typeName: TypeOfTypes,
value: T,
optional?: boolean): [T | undefined, Error[]];
Validates that a value matches the expected type, returning the value and any errors.
| Type Parameter |
|---|
T |
| Parameter | Type | Default value | Description |
|---|---|---|---|
typeName | TypeOfTypes | undefined | The expected type name. |
value | T | undefined | The value to validate. |
optional | boolean | false | If true, undefined values are accepted without error. |
[T | undefined, Error[]]
A tuple of [value or undefined, array of errors].
type AnyFunction = (...args: unknown[]) => unknown;
A function type that accepts any arguments and returns unknown.
| Parameter | Type |
|---|---|
...args | unknown[] |
unknown
type Brand<T, B> = T & { [K in keyof B]: B[K] };
Creates a branded type by intersecting base type T with brand type B, enabling nominal typing in TypeScript.
| Type Parameter |
|---|
T |
B |
type FieldType =
| "string"
| "number"
| "object"
| "symbol"
| "undefined"
| "null"
| "array"
| "function";
Union of string literals representing the possible types of an object field.
type IdentityFunction<T> = (value: unknown) => value is T;
A type guard function that narrows an unknown value to type T.
| Type Parameter |
|---|
T |
| Parameter | Type |
|---|---|
value | unknown |
value is T
type ObjectTypeShape = Record<string | number | symbol, FieldType>;
Describes the expected shape of an object by mapping each key to its expected field type.
type RecordKey = string | number | symbol;
A union of valid object key types.
type TypeOfTypes =
| "string"
| "number"
| "object"
| "array"
| "buffer"
| "null"
| "undefined"
| "bigint"
| "boolean"
| "function"
| "symbol";
Union of string literals representing the possible results of the extended typeOf function.
type TypedArray = TypedValue[];
An array of TypedValue elements.
type TypedKey<T> = T extends string ? T : string | number | symbol;
A valid key for a typed object. Defaults to string | number | symbol unless narrowed by T.
| Type Parameter | Default type |
|---|---|
T extends string | void | void |
type TypedObject =
| {
[key: string | number | symbol]: TypedValue;
}
| object;
An object whose keys are TypedKey and whose values are TypedValue.
type TypedValue =
| bigint
| string
| number
| boolean
| null
| TypedObject
| TypedArray
| Function
| symbol
| undefined;
A value that can appear in a typed object tree (primitives, objects, arrays, functions, and symbols).
Part of sdk-js
See the LICENSE file for license details
FAQs
Base functionality used throughout XY Labs TypeScript/JavaScript libraries
The npm package @xylabs/typeof receives a total of 12,639 weekly downloads. As such, @xylabs/typeof popularity was classified as popular.
We found that @xylabs/typeof demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 5 open source maintainers collaborating on the project.
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