invariant

Asserts that a given condition is true. If the condition is false, an error is thrown with the provided message.

Signature

function invariant(condition: unknown, message: string): asserts condition;

Parameters

• condition (unknown): The condition to evaluate.
• message (string): The error message to throw if the condition is false.

Returns

(void): Returns void if the condition is true.

Throws

Throws an error with the specified message if the condition evaluates to false.

Examples

// This call will succeed without any errors
invariant(true, 'This should not throw');

// This call will fail and throw an error with the message 'This should throw'
invariant(false, 'This should throw');

// Example of using invariant with a condition
invariant(condition, 'Expected condition is false');

// Ensure that the value is neither null nor undefined
invariant(value !== null && value !== undefined, 'Value should not be null or undefined');

// Example of using invariant to check if a number is positive
invariant(number > 0, 'Number must be positive');