backwards compatibilify your callback functions while migrating apis to promises
var callbackify =var getUserById =// later in your code, we can use a callback// but for newer code, we can consume it as a promise
callbackify will also preserve the
this context of your functions:
getUserById// the underlying promise-returning function is called with the supplied context argument
Normally, callbackify will only work with fixed-parameter-length functions, and will use the declared parameter length to determine if the extra callback argument is present. If you need to use callbackify with variadic functions, or functions that don't declare their full argument list, you can use:
// options argument is optionalvar getUserById = callbackify// we can do either of these
Note that this will not work if the last argument your function can take is a function, as that last argument will always be detected as a callback function.
Takes a Promise-returning function
fn and returns a new function which can return a Promise or take a callback as the last parameter. If a callback is supplied, the function returns void. If no callback is supplied, the promise is returned.
$ npm install callbackify
From package root:
$ npm install $ npm test
MIT. (c) MMXIII jden email@example.com. See LICENSE.md