core-js/internals/iterate.js

Standard library

var anObject = require('../internals/an-object');
var isArrayIteratorMethod = require('../internals/is-array-iterator-method');
var toLength = require('../internals/to-length');
var bind = require('../internals/bind-context');
var getIteratorMethod = require('../internals/get-iterator-method');
var callWithSafeIterationClosing = require('../internals/call-with-safe-iteration-closing');
var BREAK = {};

var exports = module.exports = function (iterable, fn, that, ENTRIES, ITERATOR) {
  var boundFunction = bind(fn, that, ENTRIES ? 2 : 1);
  var iterator, iterFn, index, length, result, step;

  if (ITERATOR) {
    iterator = iterable;
  } else {
    iterFn = getIteratorMethod(iterable);
    if (typeof iterFn != 'function') throw TypeError('Target is not iterable');
    // optimisation for array iterators
    if (isArrayIteratorMethod(iterFn)) {
      for (index = 0, length = toLength(iterable.length); length > index; index++) {
        result = ENTRIES ? boundFunction(anObject(step = iterable[index])[0], step[1]) : boundFunction(iterable[index]);
        if (result === BREAK) return BREAK;
      } return;
    }
    iterator = iterFn.call(iterable);
  }

  while (!(step = iterator.next()).done) {
    if (callWithSafeIterationClosing(iterator, boundFunction, step.value, ENTRIES) === BREAK) return BREAK;
  }
};

exports.BREAK = BREAK;