// 22.1.3.3 Array.prototype.copyWithin(target, start, end = this.length) 'use strict'; var toObject = require('./$.to-object') , toIndex = require('./$.to-index') , toLength = require('./$.to-length'); module.exports = [].copyWithin || function copyWithin(target/*= 0*/, start/*= 0, end = @length*/){ var O = toObject(this) , len = toLength(O.length) , to = toIndex(target, len) , from = toIndex(start, len) , $$ = arguments , end = $$.length > 2 ? $$[2] : undefined , count = Math.min((end === undefined ? len : toIndex(end, len)) - from, len - to) , inc = 1; if(from < to && to < from + count){ inc = -1; from += count - 1; to += count - 1; } while(count-- > 0){ if(from in O)O[to] = O[from]; else delete O[to]; to += inc; from += inc; } return O; };