Method insert

src/util/Array.mjs:64–89

* Inserts an item or Array of items to an array in case it does not already exist. * Duplicates will only get matched by reference. * @param {Array} arr * @param {Number} index * @param {*} items * @returns {Array}

(arr, index, items)

     * @returns {Array}
     */
    static insert(arr, index, items) {
        if (!Array.isArray(items)) {
            items = [items]
        }

        let len = items.length -1,
            i   = len,
            currentIndex, item;

        // Iterate backwards
        for (; i > -1; i--) {
            item = items[i];

            currentIndex = arr.indexOf(item);

            if (index !== currentIndex) {
                if (currentIndex > -1) {
                    this.move(arr, currentIndex, index)
                } else {
                    arr.splice(index, 0, item)
                }
            }
        }

        return arr
    }

    /**
     * Returns an array of items which are present in array1 and array2