Polyfills.js

// Polyfills.js
//
// Created by Milad Nazeri on 2018-06-19
//
// Copyright 2018 High Fidelity, Inc.
//
// Distributed under the Apache License, Version 2.0.
// See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
//
// Polyfills for missing standard JS functionality 

function registerPolyfills() {

    if (typeof Object.assign !== 'function') {
        // Must be writable: true, enumerable: false, configurable: true
        Object.defineProperty(Object, "assign", {
            value: function assign(target, varArgs) { // .length of function is 2
                'use strict';
                if (target == null) { // TypeError if undefined or null
                    throw new TypeError('Cannot convert undefined or null to object');
                }

                var to = Object(target);

                for (var index = 1; index < arguments.length; index++) {
                    var nextSource = arguments[index];

                    if (nextSource != null) { // Skip over if undefined or null
                        for (var nextKey in nextSource) {
                            // Avoid bugs when hasOwnProperty is shadowed
                            if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
                                to[nextKey] = nextSource[nextKey];
                            }
                        }
                    }
                }
                return to;
            },
            writable: true,
            configurable: true
        });
    }
    if (!Array.prototype.findIndex) {
        Object.defineProperty(Array.prototype, 'findIndex', {
            value: function (predicate) {
                // 1. Let O be ? ToObject(this value).
                if (this == null) {
                    throw new TypeError('"this" is null or not defined');
                }

                var o = Object(this);

                // 2. Let len be ? ToLength(? Get(O, "length")).
                var len = o.length >>> 0;

                // 3. If IsCallable(predicate) is false, throw a TypeError exception.
                if (typeof predicate !== 'function') {
                    throw new TypeError('predicate must be a function');
                }

                // 4. If thisArg was supplied, let T be thisArg; else let T be undefined.
                var thisArg = arguments[1];

                // 5. Let k be 0.
                var k = 0;

                // 6. Repeat, while k < len
                while (k < len) {
                    // a. Let Pk be ! ToString(k).
                    // b. Let kValue be ? Get(O, Pk).
                    // c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
                    // d. If testResult is true, return k.
                    var kValue = o[k];
                    if (predicate.call(thisArg, kValue, k, o)) {
                        return k;
                    }
                    // e. Increase k by 1.
                    k++;
                }

                // 7. Return -1.
                return -1;
            },
            configurable: true,
            writable: true
        });
    }

    if (!Function.prototype.bind) {
        Function.prototype.bind = function (oThis) {
            if (typeof this !== 'function') {
                // closest thing possible to the ECMAScript 5
                // internal IsCallable function
                throw new TypeError('Function.prototype.bind - what is trying to be bound is not callable');
            }

            var aArgs = Array.prototype.slice.call(arguments, 1),
                fToBind = this,
                fNOP = function () { },
                fBound = function () {
                    return fToBind.apply(this instanceof fNOP
                        ? this
                        : oThis,
                        aArgs.concat(Array.prototype.slice.call(arguments)));
                };

            if (this.prototype) {
                // Function.prototype doesn't have a prototype property
                fNOP.prototype = this.prototype;
            }
            fBound.prototype = new fNOP();

            return fBound;
        };
    }

    if (!Math.sign) {
        Math.sign = function(x) {
          return ((x > 0) - (x < 0)) || +x;
        };
      }
}

module.exports = registerPolyfills;