🔺🔸 Facebook's PropTypes standalone extensible implementation for browser and server
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Type Name Latest commit message Commit time
Failed to load latest commit information.



npm Travis npm

Facebook's PropTypes interface implementation for client and server, reusable and extensible. It produce error reports instead of throwing or printing into console. It could work without React.

Table of Contents


Via npm:

npm i typed-props

Or via unpkg.com:

<script src="https://unpkg.com/typed-props@0/dist/typed-props.js"></script>
<script src="https://unpkg.com/typed-props@0/dist/typed-props.min.js"></script>

Complete usage guide.


Custom types check:

import Type, {check} from 'typed-props';

check(1, Type.number);
check({count: 1}, Type.shape({count: Type.number}));

Experimental Features. Decorators to check function arguments and return value:

import Type, {args, result} from 'typed-props';

class Arith {
    // Fixed arguments length example
    @args(Type.number, Type.number)
    add(a, b) {
        return a + b;

    // Variadic argument's length example
    @args(Type.number, [Type.number])
    addAll(a = 0, ...numbers) {
        return numbers.reduce((sum, b) => sum + b, a);

NOTE! If invalid arguments passed Error with type TypeError and property issues will be thrown.

Standard checkers

Standard checkers are those which are provided by Facebook's PropTypes:

import Type from 'typed-props';

// Object which properties should pass all checks.
const shape = Type.shape({
    // Object type rules

    // Any value except of undefined
    anything: Type.isRequired,
    // Number property
    number: Type.number,
    // String property
    string: Type.string,
    // Boolean property
    bool: Type.bool,
    // Object property
    object: Type.object,
    // Array property
    array: Type.array,
    // Array property
    func: Type.func,
    // Symbol property
    symbol: Type.symbol,
    // Property which value is instance of Date
    instanceOf: Type.instanceOf(Date),

    // Complex rules

    // One of check if value is in list of passed primitives
    // It works like an enum
    oneOf: ['one', 'two'],
    // Check if all array values match the passed TypedProps
    arrayOf: Type.number,
    // Check if value is matched any of passed TypedProps.
    oneOfType: Type.oneOfType([
    // Check if all object properties passes the TypedProps.
    objectOf: Type.objectOf(Type.number),

const issues = Type.check({}, shape); // => [{path:['anything'], rule: 'isRequired', details: {is: false}}]

Result of check call is array of issues. If there is no issues, this array will be empty.

Non-standard checkers

TypedProps have it's own custom checkers which help in difficult cases like value-dependent type check:


(...Function|TypedProps) -> TypedProps

This checker allow to dynamically switch between types depending on input value. It selects the first arguments that is not a function or if it's function and it returns something truly. Then use it as type to check.

    (value) => (typeof value === 'string') && Type.string,
    (value) => (typeof value === 'number') && Type.number,

Custom checkers

TypedProps could be inherited or extended with new rules.

// Extend Type with custom checker.
Type.addProperty('infinity', (value) => {
    if (value === undefined) { // Skip empty values

    return value === Infinity;

// Inherit Type in new class
class MyType extends Type {}

MyType.addMethod('equals', (value, needle) => {
    if (value === undefined) {

    return value === needle;

// Any Type' ancestor should be validated by Type
Type.check(5, MyType.equals(5)); // -> []
MyType.check(5, MyType.equals(5)); // -> []

// MyType uses Type's checker `infinity`
Type.check(Infinity, MyType.infinity); // -> []



(value:*, type:TypedProps) -> Array.<Issue>

Validate value to satisfy type requirements. Always produce an Array.


(name:String, [transform:TransformFunc,] checker:CheckerFunc) -> void
  • name - New TypedProps property name.
  • transform - Function that transform params before they got into checker. It works once when type is configuring.
  • checker - Checker function.

Add new checker which receive params. This method can receive transform function which will convert checker call arguments into internal representation.

// Define checker
Type.addMethod('isFinite', (value, expect) => {
    return isFinite(value) === expect;
// ... or with transform param
Type.addMethod('isFinite', (expect = true) => ({expect}), (value, {expect}) => {
    return isFinite(value) === expect;

// Use it
const type = TypedProps.isRequired.number.isFinite(true);


(name:String, checker:CheckerFunc) -> void
  • name - New TypedProps property name.
  • checker - Checker function.

Define checker which has no parameters.

// Define checker
Type.addProperty('isFinite', (value) => {
    return isFinite(value) === true;

// Use it
const type = Type.isRequired.number.isFinite;


(type:TypedProps, name:string) -> null|*[]
  • type - Target type.
  • name - Checker name.
  • = Returns array of checker arguments or null if checker is not found.

CheckerFunc Type

(value:*, ...params:*) -> Boolean|Issue|Array.<Issue>|void

Checker function is calling from TypedProps to verify value. This function should return boolean value, Issue or array of Issue objects.

Usually checker function should not check undefined value.

TransformFunc Type

(params:...*) -> Object

Transform function receive arguments passed to checker method call and convert it into object.

Issue Type

    path: Array.<String|Number>
    rule: String,
    details: Object,

Object representing validation failure.


Copyright © 2018, Rumkin. Released under MIT License.