Move item to first position in array but keep order

March 17, 2022

I am a bit stuck with this problem. I am trying to write a function that takes an index and moves the item with that index in an array to the first position while maintaining the subsequential order of the other items.

const unorderedArr = [item1, item2, item3, item4]
const reorderArr = (i, arr) => { 
 ...
}

const reorderedArr = reorderArr(2, unorderedArr)
// [item3, item4, item1, item2]

Happy for any pointers!

>Solution :

You could use a swapping with the previous item until the index is zero.

const
    reorderArr = (array, i) => {
        while (i) {
            [array[i], array[i - 1]] = [array[i - 1], array[i]];
            i--;
        }
        return array;
    };

console.log(...reorderArr(['item1', 'item2', 'item3', 'item4'], 2));