lib/polyfill.js

/**
 * @external {Object.assign} https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
 */
/* istanbul ignore next */
if (!Object.assign) {
    Object.defineProperty(Object, 'assign', {
        enumerable: false,
        configurable: true,
        writable: true,
        value: function(target, firstSource) {
            'use strict';

            if (target === undefined || target === null) {
                throw new TypeError('Cannot convert first argument to object');
            }

            var to = Object(target);
            var i = 1;

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

                if (nextSource === undefined || nextSource === null) {
                    continue;
                }

                var keysArray = Object.keys(Object(nextSource));
                var nextIndex = 0, len = keysArray.length;

                for (; nextIndex < len; nextIndex++) {
                    var nextKey = keysArray[nextIndex];
                    var desc = Object.getOwnPropertyDescriptor(
                        nextSource, nextKey);

                    if (desc !== undefined && desc.enumerable) {
                        to[nextKey] = nextSource[nextKey];
                    }
                }
            }

            return to;
        }
    });
}

/**
 * @external {Array.indexOf} https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf
 */
/* istanbul ignore next */
if (!Array.prototype.indexOf) {
    Array.prototype.indexOf = function(searchElement, fromIndex) {
        var k;

        if (this == null) {
            throw new TypeError('"this" is null or not defined');
        }

        var O = Object(this);
        var len = O.length >>> 0;

        if (len === 0) {
            return -1;
        }

        var n = +fromIndex || 0;

        if (Math.abs(n) === Infinity) {
            n = 0;
        }

        if (n >= len) {
            return -1;
        }

        k = Math.max(n >= 0 ? n : len - Math.abs(n), 0);

        while (k < len) {
            if (k in O && O[k] === searchElement) {
                return k;
            }

            k++;
        }

        return -1;
    };
}