trjhtr

currentUserPosts will have a post object with an id that either matches a tempId, an Id, or nothing.

If there's a tempId match there won't be an id match and vice versa.

This code works but there's something about it I don't like. How can it be refactored?

let postIndex;
postIndex = currentUserPosts.findIndex(post => post.id === upsertParams.tempId);
if (postIndex === -1) 
 postIndex = currentUserPosts.findIndex(post => post.id === upsertParams.id);

if (postIndex === -1) 
 currentUserPosts.push(upsertParams);
 else 
 currentUserPosts[postIndex] = upsertParams;

Complete function:

const upsertIntoApolloCache = (upsertParams) => 
 try 
 const data = client.readQuery(
 query: USER_POSTS_QUERY,
 );
 const currentUserPosts = data.currentUser.posts;

 const postIndex = currentUserPosts.findIndex(
 post => post.id === upsertParams.tempId catch (error) 
 console.log('!!ERROR in upsertIntoApolloCache!!', error);
 
;

You can group the two conditions for finding into a single || condition, since the post.id can match only one of tempId or id.

let postIndex = currentUserPosts.findIndex(post => 
 return post.id === upsertParams.id );

if (postIndex === -1) 
 currentUserPosts.push(upsertParams);
 else 
 currentUserPosts[postIndex] = upsertParams;

You could, if possible, also change the currentUserPosts from array to a dictionary mapping your post.id to the post itself. This entirely depends on your further usage of the currentUserPosts across application.

Based on updated question content:

let currentUserPosts = 
for (let post of data.currentUser.posts) 
 currentUserPosts[post.id] = post

This way, you'd only have to check against id using the in operation:

let newId = upsertParams.id || upsertParams.tempId
if (newId in currentUserPosts)
 // do unspeakable things