index.js
function _join(arr1, arr2) {
	var len = arr1.length > arr2 ? arr1.length : arr2.length
	var joinedArr = []
	while(len --) {
		joinedArr.push(arr1.shift())
		joinedArr.push(arr2.shift())
	}
	// merge remains
	return joinedArr.concat(arr1).concat(arr2)
}
function _join(arr1, arr2) {
	var len = arr1.length > arr2 ? arr1.length : arr2.length
	var joinedArr = []
	while(len --) {
		joinedArr.push(arr1.shift())
		joinedArr.push(arr2.shift())
	}
	// merge remains
	return joinedArr.concat(arr1).concat(arr2)
}
function _join ( arr1 , arr2 ) { var len = arr1 . length > arr2 ? arr1 . length : arr2 . length var joinedArr = [ ] while ( len -- ) { joinedArr . push ( arr1 . shift ( ) ) joinedArr . push ( arr2 . shift ( ) ) } // merge remains return joinedArr . concat ( arr1 ) . concat ( arr2 ) }
join arr2's items to arr
@param  {Array} arr1  odd number index items
@param  {Array} arr2  even number index items
@return {Array}       new array with join result
join arr2 s items to arr