recursion-perpetua.js

const items = [
  { id: 2, seqId: 4, parent: 5, name: "index.tsx" },
  { id: 3, seqId: 3, parent: 1, name: "Sidebar" },
  { id: 4, seqId: 5, parent: 1, name: "Table" },
  { id: 7, seqId: 5, parent: 5, name: "SelectableDropdown.tsx" },
  { id: 5, seqId: 2, parent: 1, name: "AssignmentTable" },
  { id: 1, seqId: 1, parent: null, name: "components" },
  { id: 6, seqId: 2, parent: null, name: "controllers" },
  { id: 8, seqId: 8, parent: 3, name: "controllers" },
]


function transformItems(items, i=0, sorted=false) {
  const next = i+1
  const tmp = items[i]
  const newData = items[next] || null

  if(sorted) {
    // break recursion when index of array is out of bound
    if(!Boolean(items[i])) {
      return items
    }
    // Initialize depth value
    tmp.depth = Boolean(tmp.depth) ?tmp.depth :0
    let stillChecking = true
    // Let loop untill we know
    // there are no matching items
    while(stillChecking) {
      let mustCheck = false;
      // Loop in reserve order
      // So that everytime the item is added
      // it will be on ascending order
      for(let x=items.length; x--;) {
        const item = items[x]
        // Lets skip current item and
        // items that already has depth
        if(item.id == tmp.id || Boolean(item.depth)) {
          continue;
        }
        if(Boolean(item.parent) && item.parent == tmp.id) {
          // What 2 items
          // And place it under its parent
          const toTransfer = items.splice(x,1)[0]
          toTransfer.depth = tmp.depth+1
          items.splice(i+1, 0, toTransfer)
          mustCheck = true
        }
      }
      // Are there still checking?
      if(!mustCheck) {
        stillChecking = false
      }
    }
    return transformItems(items, i+1, true)
  } else {
    // swap data when current seq id is more than to its next item
    if(newData) {
      if(tmp.seqId > newData.seqId) {
        items[i] = newData
        items[next] = tmp
      }
    }

    let notSorted = false;
    // Lets check if all are all sorted
    for(let x=0; x < items.length; x++) {
      if(Boolean(items[x+1])) {
        if(items[x].seqId > items[x+1].seqId) {
          notSorted = true;
          break;
        }  
      }
    }
    if(notSorted) {
      // Continue sorted
      return transformItems(items, items.length-1 == i ?0 :i+1);
    } else {
      // Manage depth
      return transformItems(items, 0, true);
    }
  }
  return items
}

const finalItems = transformItems(items);

console.log(finalItems)