Promisifies a function that expects a callback with a single (result) argument
npm install promisify-simple-callbackPromisifies a function that expects a callback with a single (result) argument - in other words, a callback that looks like function(result) { ... } - in what should be a reasonably performant manner.
Because sometimes, a module just doesn't conform to the Node.js callback convention.
WTFPL or CC0, whichever you prefer. A donation and/or attribution are appreciated, but not required.
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Pull requests welcome. Please make sure your modifications are in line with the overall code style, and ensure that you're editing the files in src/, not those in lib/.
Build tool of choice is gulp; simply run gulp while developing, and it will watch for changes.
Be aware that by making a pull request, you agree to release your modifications under the licenses stated above.
``javascript
var Promise = require("bluebird");
var promisifySimpleCallback = require("promisify-simple-callback");
/ Pretend that brokenAsyncMethod comes from a third-party library. /
function brokenAsyncMethod(someArg, options, cb) {
doSomething(options, function(err, result) {
cb(result);
})
}
/ Promisify it! /
var promisifiedAsyncMethod = promisifySimpleCallback(brokenAsyncMethod, [null, {}]);
/ Now we can use it normally. /
Promise.try(function() {
return promisifiedAsyncMethod("foobar");
}).then(function(result) {
console.log("Done!", result);
});
`
Promisifies the given func. The promisified method will also catch any synchronous errors, and propagate them as rejections.
You can also specify default argument values; often, there are optional arguments that come before the callback, and by specifying default values, you can make these arguments really optional.
Because promisification works by appending a callback at the end of the arguments list, you would otherwise have to include all the optional arguments just to make sure the callback ends up in the right place.
* __func__: The callback-expecting function to promisify.
__defaults__: Optional.* An array of default arguments to fill in. Any argument for which you specify null will be skipped - that is, it will be left exactly as is. This means that, for an unspecified argument, it is left to undefined`.