guards

mauss/guards

Collection of guard functions to pass TypeScript checks.

import { :util } from 'mauss/guards';

bulwark

A guard for exhaustive checks with if/else/switch statements, this will help branching logic in consuming enumeration and union types.

import { bulwark } from 'mauss/guards';

let key = 'a' as 'a' | 'z';
switch (key) {
	case 'a':
		return key.charCodeAt();
	default:
		// Argument of type 'string' is not assignable to parameter of type 'never'.
		return bulwark(key);
}

exists

A guard that returns true if the input is not nullish or an empty string.

nullish

A guard that returns true if the input is null or undefined.

truthy

A guard that returns true if the input is truthy in general.

natural

A number guard that returns true if the input exists or is a number greater than 0.

whole

A number guard that returns true if the input exists or is a number greater than or equal to 0.

not

A utility guard that takes in any guards above and negates the result. For example,

• not(exists) will return true if the input is nullish or an empty string
• not(natural) will return true if the input exists or is a number less than or equal to 0.

lowercase

A string guard that returns true if the input is a string with all lowercase characters.

uppercase

A string guard that returns true if the input is a string with all uppercase characters.