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Build Status

Thin wrapper arround Node.js modules that makes the async functions promise aware. The wrapped methods return a promise the represents the value of the async operation. Traditional callbacks still work, allowing for a transparent drop-in.


Wrap a single function

var nodeThen, fs, readFileThen;
nodeThen = require('node-then');
fs = require('fs');
readFileThen = nodeThen.wrapFunction(fs.readFile, fs);
readFileThen('path/to/file').then(function (fileConent) { ... });

Wrap an object

var nodeThen, fs, fsThen;
nodeThen = require('node-then');
fs = require('fs');
fsThen = nodeThen.wrapObject(fs, function isEligible(name, prop) {
    return typeof prop === 'function';
fsThen.readFile('path/to/file').then(function (fileConent) { ... });

Test Suite

Our test suite uses Buster.js for correctness and Benchmark.js for performance.

Running the correctness tests: $ npm test

Running the performance tests: $ npm run-script benchmark

Performance Impact

Wrapping a callback with a promise will be slower than the native callbacks. The question should be how much slower vs what benefit. Ultimatly, it's up to each developer to decide if the cost/benefit is worthwhile.

native callback x 749 ops/sec ±0.37% (24 runs sampled)
promised callback x 697 ops/sec ±0.59% (87 runs sampled)
promised promise x 710 ops/sec ±0.59% (75 runs sampled)
promised callback is 0.084 ms slower than native callback
promised promise is 0.069 ms slower than native callback

Change Log


  • first release