Rewrite code without using let javascript

Question

Assuming reassignment of variable can lead to bugs what hard to debug, I am looking for options not to use let in this example. Please advice.

function getNodeById<F extends ISomeOptions>(
   optionsList: F[],
   nodeId: string): F | null {

   let result: ISomeOptions | null = null;

   optionsList.forEach((node) => {
     if (node.id === nodeId) {
       return (result = node);
     }

     if (
       Array.isArray(node.children) &&
       getNodeById(node.children, nodeId)
     ) {
       return (result = getNodeById(node.children, nodeId));
     }

     return null;
   });

   return result;
 }

This is typescript. Why do you want to remove let? – Daniel A. White May 29 '22 at 13:36 — Daniel A. White, May 29 '22 at 13:36

marekvospel · Answer 1 · 2022-05-29T14:32:54.517

0

You can use Array.find

function getNodeById<F extends ISomeOptions>(
   optionsList: F[],
   nodeId: string): F | null {

   return optionsList.find((node) => {
      if (node.id === nodeId) return node
      if (Array.isArray(node.children) {
         // getNodeById is a recursive function, so it could be expensive to run it twice.
         let child = getNodeById(node.children, nodeId)
         if (child) return child
      }
   });

   return result;
 }

edited May 29 '22 at 14:32

answered May 29 '22 at 13:42

marekvospel

412
4
9

1

`some` always return `true` or `false`, not `F`. `find` is closer to what you want, but still not quite. – Alexey Romanov May 29 '22 at 14:26
my bad, got some and find mixed up – marekvospel May 29 '22 at 14:32
As I said, not quite; in the `if (child) return child` case `find` will return `node` because `child` is truthy. – Alexey Romanov May 29 '22 at 14:35
This function is supposed to return a node with id of `nodeId`, not a node, that has a child with id of `nodeId`. (In original code `return (result = getNodeById(node.children, nodeId));`) – marekvospel May 29 '22 at 14:43

score 0 · Accepted Answer · answered May 29 '22 at 14:28

You want a simple loop which you can immediately return from instead of forEach:

function getNodeById<F extends ISomeOptions>(
   optionsList: F[],
   nodeId: string): F | null {

   for (const node of optionsList) {
     if (node.id === nodeId) {
       return node;
     }

     if (Array.isArray(node.children)) {
       const node1 = getNodeById(node.children, nodeId);
       if (node1) {
         return node1;
       }
     }
   }

   return null;
 }

Rewrite code without using let javascript

2 Answers2