Convert node-style callback-based functions into promise-based equivalents for easier composition
npm install promoConvert node-style callback-based functions into promise-based equivalents for easier composition.
``
$ npm i promo
`js
var promo = require( 'promo' );
// Take a standard function...
var standard = function ( arg1, arg2, arg3, callback ) {
// callback is eventually called with two arguments - an error
// (if applicable) and the result;
};
// ...and create a promise-returning equivalent
var promisified = promo( standard );
// Then, instead of doing this...
standard( a, b, c, function ( err, result ) {
if ( err ) {
return handleError( err );
}
handleResult( result );
});
// ...do this:
promisified( a, b, c ).then( handleResult, handleError );
`
Real-world example:
`js`
var readFile = promo( require( 'fs' ).readFile ),
writeFile = promo( require( 'fs' ).writeFile ),
glob = promo( require( 'glob' ) ),
mkdirp = promo( require( 'mkdirp' ) );
If necessary, you can pass in the context as a second argument:
`jsthis
var someModule = {
someMethod: function ( callback ) {
// because this method uses , we need to
// pass in a context
this.doSomething( callback );
}
};
var promisified = promo( someModule.someMethod, someModule );
`
If you convert a function that references this, and don't pass in a context, promo will warn you about it.
Any properties of the function are available after it has been promisified:
`js`
var glob = promo( require( 'glob' ) );
var matches = glob.sync( 'dir/**' ); // still works
The Promise object used under the hood is exposed as promo.Promise`.
This module uses es6-promise by Jake Archibald.
MIT.