asBoolean

Introduction

asBoolean is a small library to help cast common types in Javascript as boolean instead of having to rely on hacks directly in your code.

The main motivation is to create a more reliable way of interaction with booleans in a human friendly way. This point, however, is certainly arguable.

Installation

To install run the following command:

npm install @noxy/as-boolean@latest

Typescript types are already available in the library so no need to get external types.

Usage

To use this library, simply import the function from the library and call it with the value you want converted to a boolean:

import {asBoolean} from "@noxy/as-boolean";

const bool: boolean = asBoolean("true");

// writes the boolean: true
console.log(bool);

With strings

The following values are regarded as true:

• "1"
• "+"
• "y"
• "yes"
• "true"

The following values are regarded as false:

• "-1"
• "0"
• "-"
• "n"
• "no"
• "false"

Strings are case-insensitive. Any other string will return an error.

With numbers or bigint

The number 1 is regarded as true, the numbers 0 and -1 are regarded as false Bigint follow the same rules as the number primitive type.

With objects

In general, objects are regarded as true if they contain any properties, and as false if they contain no properties. The following are exceptions to that rule:

With arrays

Arrays are regarded as true if they contain any elements, and are regarded as false if they contain no elements.

With Buffer objects

Buffer objects are regarded as true if they contain any data, and are regarded as false if they contain no data.

With Date objects

Date objects are regarded as true if their UNIX timestamp value is greater than 0, and false if they are equal to or less than 0.

With asBoolean method

If the object contains an asBoolean() method, it will be invoked with the this argument being the object itself and no arguments. The resulting value of the method will be used as the return value of the asBoolean call.

With symbols

Symbols have their string value read and are then regarded as strings

With functions

Functions are always regarded as true

With undefined and null

Undefined and null are always regarded as false