A basic but performant promise implementation.
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Latest commit eaf9fd8 Mar 6, 2018



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lie is a small, performant promise library implementing the Promises/A+ spec (Version 1.1).

Originally a fork of Ruben Verborgh's promiscuous, with version 2.6 it became a fork of ayepromise by Chris Burgmer.

npm install lie
var Promise = require('lie');
// or use the pollyfill


Either use it with browserify (recommended) or grab one of the files from the dist folder:

  • lie.js/lie.min.js exposes 'Promise' either as a UMD module or from the global scope, depending on if a CJS or AMD loader is available.
  • lie.polyfill.js/lie.polyfill.min.js adds 'Promise' to the global scope only if it's not already defined (not a UMD).


Implements the standard ES6 api:

new Promise(function(resolve, reject){
    doSomething(function(err, result) {
        if (err) {
        } else {
}).then(function (value) {
    //on success
}, function (reason) {
    //on error
}).catch(function (reason) {
    //shortcut for error handling

    //array of promises or values
]).then(function ([/* array of results */]));

    //array of promises or values
// either resolves or rejects depending on the first value to do so

Unhandled Rejections

In Node.js, lie emits an unhandledRejection event when a rejected promise isn't caught, in line with how io.js does it. This allows it to act as a promise shim in both Node.js and the browser.