Object API

isPlainObject Plain

Checks whether a value is a plain object.

Signature

export function isPlainObject(value: unknown): value is Record<PropertyKey, unknown>;

Example

import { isPlainObject } from "@fast-china/utils";

const result = isPlainObject({});

Input

Input	Type	Required / default	Description
value	unknown	Required	Any value to check.

Returns

Value	Type	Description
result	value is Record<PropertyKey, unknown>	true when the prototype is Object.prototype or null.

hasOwn Ownership

Safely checks for an object's own property.

Signature

export function hasOwn<ObjectType extends object, Key extends PropertyKey>(value: ObjectType, key: Key): key is Key & keyof ObjectType;

Example

import { hasOwn } from "@fast-china/utils";

const result = hasOwn({}, "profile");

Input

Input	Type	Required / default	Description
value	ObjectType	Required	Object to check.
key	Key	Required	String, number, or Symbol property key.

Returns

Value	Type	Description
result	key is Key & keyof ObjectType	true for an own property, narrowing the key type.

cloneDeep Clone

Recursively creates a deep copy.

Signature

export function cloneDeep<Value>(value: Value): Value;

Example

import { cloneDeep } from "@fast-china/utils";

const result = cloneDeep({});

Input

Input	Type	Required / default	Description
value	Value	Required	Any value to clone deeply.

Returns

Value	Type	Description
result	Value	New value of the same type, sharing no clonable nested values; primitives are returned unchanged.

isEqual Compare

Deeply compares two values for equivalence.

Signature

export function isEqual(left: unknown, right: unknown): boolean;

Example

import { isEqual } from "@fast-china/utils";

const result = isEqual([1, 2, 3], [2, 4]);

Input

Input	Type	Required / default	Description
left	unknown	Required	First value to compare.
right	unknown	Required	Second value to compare.

Returns

Value	Type	Description
result	boolean	true when the values are deeply equivalent.

pick Pick

Performs the corresponding public utility operation.

Signature

export function pick<Source extends object, const Keys extends readonly (keyof Source)[]>(
	source: Source,
	keys: Keys
): number extends Keys["length"] ? Partial<Pick<Source, Keys[number]>> : Pick<Source, Keys[number]>;
export function pick<Source extends object>(source: Source, keys: readonly PropertyKey[]): Partial<Source>;

Example

import { pick } from "@fast-china/utils";

const result = pick({ id: 1, name: "Fast" }, ["id"] as const);

Input

Input	Type	Required / default	Description
source	Source	Required	See the signature and method description.
keys	readonly PropertyKey[]	Required	See the signature and method description.

Returns

Value	Type	Description
result	Partial<Source>	Result calculated or created by the method.

omit Omit

Performs the corresponding public utility operation.

Signature

export function omit<Source extends object, const Keys extends readonly (keyof Source)[]>(
	source: Source,
	keys: Keys
): number extends Keys["length"] ? Omit<Source, Keys[number]> & Partial<Pick<Source, Keys[number]>> : Omit<Source, Keys[number]>;
export function omit<Source extends object>(source: Source, keys: readonly PropertyKey[]): Partial<Source>;

Example

import { omit } from "@fast-china/utils";

const result = omit({ id: 1, name: "Fast" }, ["id"] as const);

Input

Input	Type	Required / default	Description
source	Source	Required	See the signature and method description.
keys	readonly PropertyKey[]	Required	See the signature and method description.

Returns

Value	Type	Description
result	Partial<Source>	Result calculated or created by the method.

omitBy Omit

Conditionally omits own enumerable properties.

Signature

export function omitBy<Source extends object>(
	source: Source,
	predicate: (value: Source[keyof Source], key: keyof Source, source: Source) => unknown
): Partial<Source>;

Example

import { omitBy } from "@fast-china/utils";

const result = omitBy({ id: 1, name: "Fast" }, (_value, key) => key === "id");

Input

Input	Type	Required / default	Description
source	Source	Required	Source object; not mutated.
predicate	(value: Source[keyof Source], key: keyof Source, source: Source) => unknown	Required	Receives value, key, and source object; a truthy result omits the property.

Returns

Value	Type	Description
result	Partial<Source>	New object containing nonmatching properties.

pickBy Pick

Conditionally selects own enumerable properties.

Signature

export function pickBy<Source extends object>(
	source: Source,
	predicate: (value: Source[keyof Source], key: keyof Source, source: Source) => unknown
): Partial<Source>;

Example

import { pickBy } from "@fast-china/utils";

const result = pickBy({ id: 1, name: "Fast" }, (_value, key) => key === "name");

Input

Input	Type	Required / default	Description
source	Source	Required	Source object; not mutated.
predicate	(value: Source[keyof Source], key: keyof Source, source: Source) => unknown	Required	Receives value, key, and source object; a truthy result retains the property.

Returns

Value	Type	Description
result	Partial<Source>	New object containing matching properties.

mapValues Map

Maps own enumerable property values.

Signature

export function mapValues<Source extends object, Result>(
	source: Source,
	mapper: (value: Source[keyof Source], key: keyof Source, source: Source) => Result
): { [Key in keyof Source]: Result };

Example

import { mapValues } from "@fast-china/utils";

const result = mapValues({ first: 1, second: 2 }, (value) => value * 2);

Input

Input	Type	Required / default	Description
source	Source	Required	Source object; not mutated.
mapper	(value: Source[keyof Source], key: keyof Source, source: Source) => Result	Required	Mapper receiving value, key, and source object.

Returns

Value	Type	Description
result	{ [Key in keyof Source]: Result }	New object preserving the original keys.

shallowEqual Compare

Shallowly compares own enumerable properties using SameValue.

Signature

export function shallowEqual(left: object, right: object): boolean;

Example

import { shallowEqual } from "@fast-china/utils";

const result = shallowEqual([1, 2, 3], [2, 4]);

Input

Input	Type	Required / default	Description
left	object	Required	First object.
right	object	Required	Second object.

Returns

Value	Type	Description
result	boolean	true when own enumerable key sets and corresponding values match under SameValue.

toQueryString Query

Serializes an object into a standard URL query string.

Signature

export function toQueryString(value: Readonly<Record<string, QueryValue>>, options: QueryStringOptions = {}): string;

Example

import { toQueryString } from "@fast-china/utils";

const result = toQueryString({ page: 1, tag: ["vue", "tsx"] });

Input

Input	Type	Required / default	Description
value	Readonly<Record<string, QueryValue>>	Required	Query parameter object.
options	QueryStringOptions	Optional; defaults to {}	Sorting, whitespace encoding, and question-mark prefix options.

Returns

Value	Type	Description
result	string	URL-encoded query string; always empty when there are no parameters.

Clone and dynamic-key boundaries

Deep cloning preserves sparse slots, own enumerable string/symbol properties and cycles. Views sharing an ArrayBuffer also share its cloned buffer, with offsets and lengths preserved. Existing unsupported-type behavior remains. pick/omit are shallow operations and dynamic candidate keys are not incorrectly required.