packages/core-js/modules/es.iterator.filter.js

'use strict';
var $ = require('../internals/export');
var call = require('../internals/function-call');
var aCallable = require('../internals/a-callable');
var anObject = require('../internals/an-object');
var getIteratorDirect = require('../internals/get-iterator-direct');
var createIteratorProxy = require('../internals/iterator-create-proxy');
var callWithSafeIterationClosing = require('../internals/call-with-safe-iteration-closing');
var IS_PURE = require('../internals/is-pure');
var iteratorClose = require('../internals/iterator-close');
var iteratorHelperWithoutClosingOnEarlyError = require('../internals/iterator-helper-without-closing-on-early-error');

var filterWithoutClosingOnEarlyError = !IS_PURE && iteratorHelperWithoutClosingOnEarlyError('filter', TypeError);

var IteratorProxy = createIteratorProxy(function () {
  var iterator = this.iterator;
  var predicate = this.predicate;
  var next = this.next;
  var result, done, value;
  while (true) {
    result = anObject(call(next, iterator));
    done = this.done = !!result.done;
    if (done) return;
    value = result.value;
    if (callWithSafeIterationClosing(iterator, predicate, [value, this.counter++], true)) return value;
  }
});

// `Iterator.prototype.filter` method
// https://tc39.es/ecma262/#sec-iterator.prototype.filter
$({ target: 'Iterator', proto: true, real: true, forced: IS_PURE || filterWithoutClosingOnEarlyError }, {
  filter: function filter(predicate) {
    anObject(this);
    try {
      aCallable(predicate);
    } catch (error) {
      iteratorClose(this, 'throw', error);
    }

    if (filterWithoutClosingOnEarlyError) return call(filterWithoutClosingOnEarlyError, this, predicate);

    return new IteratorProxy(getIteratorDirect(this), {
      predicate: predicate
    });
  }
});