another-maybe

maybe

Just another maybe approach in Javascript. I did this because there was always something small missing everywhere and since it's not hard to create a maybe polyfill I did one on my own.

With version 0.0.3 there is full support of promises.

Where to use

You should use this on values where you are not sure if you get anything back. Usually using maybes the right way helps you avoiding if-then-elses.

Installation

npm install another-maybe --save-dev

How to use

Classic default value handling

const value = maybe('originalValue')
    .orValue('alternativeValue')
    .get();

Classic default value handling via callback

const value = maybe('originalValue')
    .orElse(() => 'alternativeValue')
    .get();

Usage of is method

const value = maybe('originalValue')
    .is((v) => v === 'originalValue')
    .orValue('alternativeValue')
    .get();

Usage of map method

const value = maybe('originalValue')
    .map((v) => v + '1')
    .get(); // originalValue1

Usage of for-each method

const value = maybe('originalValue')
    .forEach((v) => console.log(v))
    .get();

Usage in async operation

const test = async () => delayFunction(200);
const value = await maybe('originalValue')
    .map(async (v) => {
        await test();

        return v;
    })
    .orElse(async () => {
        await test();

        return 'alternativeValue';
    })
    .get();

Usage in an advanced async operation

const test = async () => delayFunction(200);
const value = await maybe(1)
    .map(async (v) => {
        await test();

        return v + 1;
    }) // returns Promise with value "2"
    .is(async (v) => {
        return v === 1;
    }) // returns Promise with value undefined
    .orElse(async () => {
        await test();

        return  0;
    }) // returns Promise with value 0
    .forEach((v) => {
        console.log(v);
    })
    .map(async (v) => {
        await test();

        return undefined;
    }) // returns Promise with value undefined
    .forEach((v) => {
        console.log(v);
    })
    .orValue(2) // returns Promise with value 2
    .map(async (v) => {
        await test();

        return v + 1;
    }) // returns Promise with value 3
    .get();

/* end result: value === 3 */