shim.js 1001 Bytes
'use strict';

var toInteger    = require('../../../number/to-integer')
  , toPosInt     = require('../../../number/to-pos-integer')
  , isPlainArray = require('../../is-plain-array')

  , isArray = Array.isArray, slice = Array.prototype.slice
  , hasOwnProperty = Object.prototype.hasOwnProperty, max = Math.max;

module.exports = function (start, end) {
	var length, result, i;
	if (!this || !isArray(this) || isPlainArray(this)) {
		return slice.apply(this, arguments);
	}
	length = toPosInt(this.length);
	start = toInteger(start);
	if (start < 0) start = max(length + start, 0);
	else if (start > length) start = length;
	if (end === undefined) {
		end = length;
	} else {
		end = toInteger(end);
		if (end < 0) end = max(length + end, 0);
		else if (end > length) end = length;
	}
	if (start > end) start = end;
	result = new this.constructor(end - start);
	i = 0;
	while (start !== end) {
		if (hasOwnProperty.call(this, start)) result[i] = this[start];
		++i;
		++start;
	}
	return result;
};