Reordering an Array Based on Another Array’s Order in Javascript

By K4Paul 2 Development , , ,

So I had a problem, awhile ago, where I needed to reorder elements in an array based off of the order of another array. So I basically had to capture the order from one and apply it to another. In my case, both arrays had a common id field. However, with the model I have here, I was able to order additional arrays without the id field, if I needed to, which I did 🙂

Below is my code solution.

function getNewOrder() {
    //Get an identifier from the array you want to base the order on
    const newIds = newArrayOrder.map(x => x.id);
    
    //Get an identifier from the array you want to update
    const ids = arrayToOrder.map(x => x.id);
    
    //placeholder for order
    const order = [];
    
    //loop through the ids, pushing the arrayToOrder's index of the new order ids
    //We end up with an array of indexes
    for(let i = 0; i < ids.length; i++) {
      order.push(ids.indexOf(newIds[i]));
    }
    
    //reorder the array
    reorderIds(order, arrayToOrder);
}

//Preform the reordering
function reorderIds(order, arrayToOrder){
    //Get a copy of the array we want to change
    const temp = arrayToOrder.slice(0);
    
    //loop through the indexes
    //use the indexes to place the items in the right place from the copy into the original
    for(let i = 0; i < arrayToOrder.length; i++) {
      arrayToOrder[order[i]] = temp[i];
    }
}