JarCastingthenify
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 byoptions.multiArgs - Resulting function never deoptimizes
- Supports both callback and promise style
An added benefit is that thrown 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 tofalse. -
options.multiArgs- change the behavior when callback have multiple arguments. default totrue.true- converts multiple arguments to an arrayfalse- always use the first argumentArray- converts multiple arguments to an object with keys provided inoptions.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 });
// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
// somethingAsync(a, b, c, function () {});
or use thenify.withCallback()
var thenify = require('thenify').withCallback;
var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
callback(null, a, b, c);
});
// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
// somethingAsync(a, b, c, function () {});
- Always return the first argument in callback
var thenify = require('thenify');
var promise = thenify(function (callback) {
callback(null, 1, 2, 3);
}, { multiArgs: false });
// promise().then(function onFulfilled(value) {
// assert.equal(value, 1);
// });
- Converts callback arguments to an object
var thenify = require('thenify');
var promise = thenify(function (callback) {
callback(null, 1, 2, 3);
}, { multiArgs: [ 'one', 'tow', 'three' ] });
// promise().then(function onFulfilled(value) {
// assert.deepEqual(value, {
// one: 1,
// tow: 2,
// three: 3
// });
// });
