core-js/modules/es.string.includes.js

'use strict';
var $ = require('../internals/export');
var uncurryThis = require('../internals/function-uncurry-this');
var notARegExp = require('../internals/not-a-regexp');
var requireObjectCoercible = require('../internals/require-object-coercible');
var toString = require('../internals/to-string');
var correctIsRegExpLogic = require('../internals/correct-is-regexp-logic');

var stringIndexOf = uncurryThis(''.indexOf);

// `String.prototype.includes` method
// https://tc39.es/ecma262/#sec-string.prototype.includes
$({ target: 'String', proto: true, forced: !correctIsRegExpLogic('includes') }, {
  includes: function includes(searchString /* , position = 0 */) {
    return !!~stringIndexOf(
      toString(requireObjectCoercible(this)),
      toString(notARegExp(searchString)),
      arguments.length > 1 ? arguments[1] : undefined
    );
  }
});