Cook

Execute array of callbacks

const iterate = (count, callback) =>
  [...Array(count)].map((_, i) => callback(i))

Generate empty array

const emptyArray = Array(5).fill(null)

Surgically remove one item from an array (no mutation)

    return [
        ...bigArray.slice(0, itemToRemoveIndex),
        ...bigArray.slice(itemToRemoveIndex + 1)
    ]

Surgically replace one item in an array

    return [
    ...bigArray.slice(0, itemToReplaceIndex),
        itemToInsert, //if item is not object
        { ...array[itemToReplaceIndex], ...itemToInsert }, //if item is object
        ...bigArray.slice(itemToReplaceIndex + 1)
    ]

Move elements within array

function swapInArrayByIndex(arr, i1, i2){
    let t = arr[i1];
    arr[i1] = arr[i2];
    arr[i2] = t;
}

function moveBefore(arr, el){
    let ind = arr.indexOf(el);
    if(ind !== -1 && ind !== 0){
        swapInArrayByIndex(arr, ind, ind - 1);
    }
}

function moveAfter(arr, el){
    let ind = arr.indexOf(el);
    if(ind !== -1 && ind !== arr.length - 1){
        swapInArrayByIndex(arr, ind + 1, ind);
    }
}

Create a new, shallow-copied Array instance from an iterable or array-like object.

const eventsMap: Map = {
   "2023-03-02": [1, 2, 3] 
}
const eventsArray = Array.from(eventsMap, ([date, ids]) => ({ date, ids }));
// [{ date: 2023-03-02, ids: [1, 2, 3] }]