core-js/internals/validate-string-method-arguments.js

Standard library

// helper for String#{startsWith, endsWith, includes}
var isRegExp = require('../internals/is-regexp');
var requireObjectCoercible = require('../internals/require-object-coercible');

module.exports = function (that, searchString, NAME) {
  if (isRegExp(searchString)) {
    throw TypeError('String.prototype.' + NAME + " doesn't accept regex");
  } return String(requireObjectCoercible(that));
};