or-promise

Accept a callback OR return a promise (easily).

example

const orPromise = require('or-promise')

function greetSoon (cb) {
    cb = orPromise(cb)
    setImediate(cb, null, 'hello')

    // this will return undefined if cb was provided, otherwise
    // it will return a promise
    return cb.promise
}

// we can now use our fancy function either way...
greetSoon(function (err, msg) {
    if (err) return console.error(err)
    console.log(msg)
})

// or a promise
greetSoon().then(console.log).catch(console.error)

example with default parameters

Same function as above, but using default parameters (if your JS engine supports it):

const orPromise = require('or-promise')

function greetSoon (cb = orPromise()) {
    setImediate(cb, null, 'hello')
    return cb.promise
}

api

var orPromise = require('or-promise')

cb = orPromise([cb])

When called with a (truthy) cb argument, orPromise simply returns the argument it was called with, unaltered.

If called with no argument, a function will be returned that is usable as an error-first callback. This function will have a promise property. When the returned callback is invoked, the promise property will be:

• resolved if the callback was invoked with a falsy first argument
• rejected if the callback was invoked with a truthy first argument

If resolved, the resolved value will be the 2nd argument supplied to the callback. If rejected, the error will be the 1st argument supplied to the callback.

testing

npm test

browser test

npm run browser-test

This will run the tests in all browsers (specified in .zuul.yml). Be sure to educate zuul first.

coverage

npm run open-cover

Open coverage in browser.