thenify
Promisify a callback-based function using any-promise
.
- Preserves function names
- Uses a native promise implementation if available and tries to fall back to a promise implementation such as
bluebird
- Converts multiple arguments from the callback into an
Array
, also support change the behavior by options.multiArgs
- Resulting function never deoptimizes
- Supports both callback and promise style
An added benefit is that throw
n errors in that async function will be caught by the promise!
API
fn = thenify(fn, options)
Promisifies a function.
Options
options
are optional.
-
options.withCallback
- support both callback and promise style, default to false
.
-
options.multiArgs
- change the behavior when callback have multiple arguments. default to true
.
true
- converts multiple arguments to an arrayfalse
- always use the first argumentArray
- converts multiple arguments to an object with keys provided in options.multiArgs
-
Turn async functions into promises
var thenify = require('thenify');
var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
callback(null, a, b, c);
});
- Backward compatible with callback
var thenify = require('thenify');
var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
callback(null, a, b, c);
}, { withCallback: true });
or use thenify.withCallback()
var thenify = require('thenify').withCallback;
var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
callback(null, a, b, c);
});
- Always return the first argument in callback
var thenify = require('thenify');
var promise = thenify(function (callback) {
callback(null, 1, 2, 3);
}, { multiArgs: false });
- Converts callback arguments to an object
var thenify = require('thenify');
var promise = thenify(function (callback) {
callback(null, 1, 2, 3);
}, { multiArgs: [ 'one', 'tow', 'three' ] });