ES5-compatible defer shim

README.md

ES5-compatible polyfill for Promise.defer() that will work regardless of whether the Promise constructor invokes the passed function synchronously or asynchronously.

defer.js

Promise.defer = Promise.defer || function () {
    'use strict';

    var result;

    var resolver = function (value) {
        result = result || new Promise(function (r) { r(value); });
    };

    var rejecter = function (reason) {
        result = result || new Promise(function (_, j) { j(reason); });
    };

    return {
        resolve: function (v) { resolver(v); },

        reject: function (v) { rejecter(v); },

        promise: new Promise(function (r, j) {
            if (result) {
                r(result);
            } else {
                resolver = r;
                rejecter = j;
            }
        })
    };
};

defer.min.js

Promise.defer=Promise.defer||function(){"use strict"
var n,e=function(e){n=n||new Promise(function(n){n(e)})},i=function(e){n=n||new Promise(function(n,i){i(e)})}
return{resolve:function(n){e(n)},reject:function(n){i(n)},promise:new Promise(function(o,r){n?o(n):(e=o,i=r)})}}