polyfill.js

'use strict';
// Polyfills for (old) mobile browsers and IE 11
// From https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/
if (!String.prototype.includes) {
  String.prototype.includes = function () {
    return String.prototype.indexOf.apply(this, arguments) !== -1;
  };
}

if (!String.prototype.startsWith) {
  String.prototype.startsWith = function (searchString, position) {
    position = position || 0;
    return this.substr(position, searchString.length) === searchString;
  };
}

if (!String.prototype.repeat) {
  String.prototype.repeat = function (count) {
    'use strict';
    if (this === null) {
      throw new TypeError('can\'t convert ' + this + ' to object');
    }
    var str = '' + this;
    count = +count;
    if (count < 0) {
      throw new RangeError('repeat count must be non-negative');
    }
    if (count === Infinity) {
      throw new RangeError('repeat count must be less than infinity');
    }
    count = Math.floor(count);
    if (str.length === 0 || count === 0) {
      return '';
    }
    // Ensuring count is a 31-bit integer allows us to heavily optimize the
    // main part. But anyway, most current (August 2014) browsers can't handle
    // strings 1 << 28 chars or longer, so:
    if (str.length * count >= 1 << 28) {
      throw new RangeError('repeat count must not overflow maximum string size');
    }
    var rpt = '';
    for (; ;) {
      if ((count & 1) === 1) {
        rpt += str;
      }
      count >>>= 1;
      if (count === 0) {
        break;
      }
      str += str;
    }
    // Could we try:
    // return Array(count + 1).join(this);
    return rpt;
  };
}

if (typeof Object.assign !== 'function') {
  Object.assign = function(target, varArgs) { // .length of function is 2
    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;
  };
}