I got an assignment to display comments in a recursive way, something like so:

The data I got from the server was flat, meaning:
every item in the array holds a reference to its parent, like so:

constentries=[{index:1,parent:0},{index:2,parent:1},{index:3,parent:2},......];

After thinking how to "attack" this problem, I realized
If I want a recursive object, then the easiest solution is a recursive one

Here is the function that converts a flat array to a tree array:

constarrayToTree=(arr,parent=0)=>arr.filter(item=>item.parent===parent).map(child=>({...child,children:arrayToTree(arr,child.index)}));

A quick rundown:

• We first filter theroot parent's children.
• Then we do the same to each of the children we just grabbed

My answer to the question on Stack overflow

Here is a codepen if you want to play more with the data ot the solution:

Sources that helped me:

• Styling Comment Threads