@types/invariant

What is @types/invariant?

The @types/invariant package provides TypeScript type definitions for the invariant npm package. Invariant is a utility that can be used to assert that a certain condition is true. If the condition is false, it will throw an error. The @types/invariant package doesn't contain functionality by itself but adds type support for TypeScript users using the invariant package.

What are @types/invariant's main functionalities?

Type Definitions for invariant

This code sample shows how you can use the invariant function with TypeScript type definitions provided by @types/invariant. It asserts that the divisor is not zero before performing the division.

import invariant from 'invariant';

function divide(dividend: number, divisor: number): number {
  invariant(divisor !== 0, 'Division by zero.');
  return dividend / divisor;
}

divide(10, 2); // works fine
divide(10, 0); // throws error with message 'Division by zero.'

Other packages similar to @types/invariant

assert

The assert package is a part of Node.js core modules and provides a simple set of assertion tests. It is similar to invariant in that it is used to test expressions for truthiness and throws an AssertionError if the expression evaluates to false. Unlike @types/invariant, assert is not just type definitions but an actual implementation of assertion functions.

chai

Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework. It offers more expressive assertions and expectation methods than invariant. Chai does not need separate type definitions as it includes its own TypeScript support.

expect.js

Expect.js is a minimalistic BDD-style assertions library that can be used in place of invariant for more expressive assertions. It is similar in purpose but provides a richer API for writing tests. Expect.js does not have separate type definitions and is not as TypeScript-friendly as @types/invariant.

README

Installation

npm install --save @types/invariant

Summary

This package contains type definitions for invariant (https://github.com/zertosh/invariant).

Details

Files were exported from https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/invariant.

index.d.ts

declare let invariant: invariant.InvariantStatic;

export = invariant;
export as namespace invariant;

declare namespace invariant {
    interface InvariantStatic {
        (testValue: false, format: string, ...extra: any[]): never;
        (testValue: any, format: string, ...extra: any[]): asserts testValue;
    }
}

Additional Details

• Last updated: Tue, 07 Nov 2023 03:09:37 GMT
• Dependencies: none

Credits

These definitions were written by MichaelBennett, dtinth, and Turadg Aleahmad.