TypeScript: Setting noErrorTruncation to false truncates inferred type of variables/functions; which are not errors

Having this problem as well. Investigating and debugging this issue led me to find this being introduced in merge https://github.com/microsoft/TypeScript/pull/24258.

Typescript starts truncating the output when it reaches the default hard-limit of 160 * 10 characters to prevent the server from hanging too long, even with "noErrorTruncation": true set. There’s currently no option for VS Code to disable it from the looks of it: https://github.com/microsoft/TypeScript/blob/57e2fe0462bb897e581aa489f1d6040db559d82b/src/services/utilities.ts#L1993

For people using VS Code, a quick fix would be opening <Microsoft VS Code install folder>/resources/app/extensions/node_modules/typescript/lib/tsserver.js and change ts.defaultMaximumTruncationLength = 160 at around line 12797 to something higher like ts.defaultMaximumTruncationLength = 800.

It’s not just CI, it’s usability problem. I actually like browsing (and copying) the type from the hover tip in the VSCode, and when it gets truncated it’s pretty much useless.

// from https://developer.twitter.com/en/docs/tweets/data-dictionary/overview/intro-to-tweet-json
let foo = {
  "text": "My added comments to this Tweet ---> https:\/\/t.co\/LinkToTweet",
  "user": {
    "screen_name": "TweetQuoter"
  },
  "quoted_status": {
    "text": "original message",
    "user": {
      "screen_name": "OriginalTweeter"
    },
    "place": {      
    },
    "entities": {      
    },
    "extended_entities": {      
    }
  },
  "place": {    
  },
    "entities": {
      "hashtags": [

      ],
      "urls": [
        {
          "url": "https://t.co/W1FqVrsjQk",
          "expanded_url": "https://twittercommunity.com/t/rt-with-comment-aka-quote-tweets-now-may-have-media-attached-across-twitter-apis/125539",
          "display_url": "twittercommunity.com/t/rt-with-comm…",
          "unwound": {
            "url": "https://twittercommunity.com/t/rt-with-comment-aka-quote-tweets-now-may-have-media-attached-across-twitter-apis/125539",
            "status": 200,
            "title": "RT with comment, aka Quote Tweets, now may have media attached across Twitter APIs",
            "description": "Today we’re announcing a new feature that allows userspeople on Twitter to add a GIF, video, or photo to their Retweet with comments, aka Quote Tweets. Developers will start to see additional media metadata included in the payload for Quote Tweets. Quote Tweets with media will be rendered very similarly to Tweets with media across our APIs. This rendering is an addition to the existing media field, so this should not be a breaking change for application owners, if they are already ingesting med..."
          },
          "indices": [
            162,
            185
          ]
        },
        {
          "url": "https://t.co/lXs26mCkIl",
          "expanded_url": "https://twitter.com/TwitterSupport/status/1125479034513645569",
          "display_url": "twitter.com/TwitterSupport…",
          "indices": [
            186,
            209
          ]
        }
      ],
      "user_mentions": [

      ],
      "symbols": [

      ],
      "media": [
        {
          "id": 1125490782532657153,
          "id_str": "1125490782532657153",
          "indices": [
            210,
            233
          ],
          "media_url": "http://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "media_url_https": "https://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "url": "https://t.co/T9MBCHZWcD",
          "display_url": "pic.twitter.com/T9MBCHZWcD",
          "expanded_url": "https://twitter.com/TwitterDev/status/1125490788736032770/photo/1",
          "type": "animated_gif",
          "video_info": {
            "aspect_ratio": [
              101,
              165
            ],
            "variants": [
              {
                "bitrate": 0,
                "content_type": "video/mp4",
                "url": "https://video.twimg.com/tweet_video/D56L51LV4AEEC8-.mp4"
              }
            ]
          },
          "sizes": {
            "thumb": {
              "w": 150,
              "h": 150,
              "resize": "crop"
            },
            "small": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "large": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "medium": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            }
          }
        }
      ]
    },
    "extended_entities": {
      "media": [
        {
          "id": 1125490782532657153,
          "id_str": "1125490782532657153",
          "indices": [
            210,
            233
          ],
          "media_url": "http://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "media_url_https": "https://pbs.twimg.com/tweet_video_thumb/D56L51LV4AEEC8-.jpg",
          "url": "https://t.co/T9MBCHZWcD",
          "display_url": "pic.twitter.com/T9MBCHZWcD",
          "expanded_url": "https://twitter.com/TwitterDev/status/1125490788736032770/photo/1",
          "type": "animated_gif",
          "video_info": {
            "aspect_ratio": [
              101,
              165
            ],
            "variants": [
              {
                "bitrate": 0,
                "content_type": "video/mp4",
                "url": "https://video.twimg.com/tweet_video/D56L51LV4AEEC8-.mp4"
              }
            ]
          },
          "sizes": {
            "thumb": {
              "w": 150,
              "h": 150,
              "resize": "crop"
            },
            "small": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "large": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            },
            "medium": {
              "w": 202,
              "h": 330,
              "resize": "fit"
            }
          }
        }
      ]
    }
  };

Weird. I thought I finally “fixed” it but, even with noErrorTruncation turned on, some long and complicated types still show up with ellipsis.

Is there a noInferredTypeTruncation thing I’m missing?

Turning on noErrorTruncation certainly stops some truncations, but it still doesn’t prevent others.

Yes agree here, it would be huge to at least have some tool - perhaps even something dedicated that would allow us to see the fully expanded and normalized type that typescript will use. Perhaps a custom “peek” style popup for it so that we can choose to view it only when we need to in the case of large types that would make processing type extreme.

@xbtsw Using "noErrorTruncation": true works perfectly on my end. (typescript v3.4.3)

edit: Something like noInferredTypeTruncation would be great! 👍

The hack is good to know about, but it isn’t really a solution for me. What I’m running into is that I often want to hover a type and want see the entire type (no “…”), but when I’m trying to read an error, showing entire type definitions can sometimes make the error utterly unreadable. So, some finer grained control is really needed here. Ideally, there’d be some integration between TypeScript and VSCode to provide a toggle to choose between “verbose” (types expanded) and “compact” (types truncated).

The ellipses makes it very hard to debug Pick, Omit, etc, when things went wrong.

There is one awesome extension that is just enormously cool. It allows to explore “compiled” versions of very complex types

It allows to explore not only types and interfaces, but literally anything: vars, functions, classes, promises, generics

Name: TypeScript Explorer Id: mxsdev.typescript-explorer Description: Full type information for variables, components, functions, and more in TypeScript projects! Version: 0.4.0 Publisher: mxs VS Marketplace Link: https://marketplace.visualstudio.com/items?itemName=mxsdev.typescript-explorer

function UsePromiseAllMappedTrace<
  TInputArrayElement,
  TReturnArrayElement,
>(
  arrayToMap: TInputArrayElement[],
  elementGetter: (
    currentTraceNode: IPublicActionTraceNode,
    arrayElement: TInputArrayElement,
    index: number,
  ) => Promise<TReturnArrayElement>,
): (parentTraceNode: IPublicActionTraceNode) => Promise<TReturnArrayElement[]> {}

Thanks again for the hack!

I just wanted to call out that if your VSCode config specifies the "typescript.tsdk" option, you’ll need to update the tsserver.ts in whatever location that option specifies. It would have saved me a bit of debugging time 🙃

one solution (that are not fast on the project that i works, because needs to load a bunch of things, but works very well) is the extension ts type expand.

https://github.com/d-kimuson/ts-type-expand

Make this vscode feature please - it’s annoying to configure manually.

The ellipsis makes it especially difficult to debug type issues (not type errors) involving Pick, Omit etc.

For example in a type that involves Omit I made a typo in second parameter of Omit, then in some other place I wondered why a interface property is still accepted. The ellipsis makes it difficult to trace back and find the original typo.

Thank you for your efforts sleuthing this out @Hati- !

I would hope to see this value bound as a configurable TS preference. However it is awesome to know that there is a way to hack around the limitation.

This is awesome @Zetxus - thanks so much!

For me, the path name has spaces in it which was upsetting the sed command (I couldn’t work out why), so with the help of chatGPT I managed to refactor it to use awk. Sharing here for others:

#!/bin/bash

if [ $# -lt 1 ]; then
  echo "Usage: $0 <directory_path> <new_length>?"
  exit 1
fi

directory_path="$1"
new_length="$2"

if [ -z "$2" ]
  then
    echo "No length supplied, will use default (160)"
    new_length=160
fi

file_path=$(find "$directory_path" -name "tsserver.js" 2>/dev/null)
if [ -z "$file_path" ]; then
  echo "tsserver.js file not found within directory $directory_path after recursive search"
  exit 1
fi

echo "Found tsserver.js at \"$file_path\""

# Use awk to perform the replacement
awk -v new_length="$new_length" '{sub(/var defaultMaximumTruncationLength = [0-9]+;/, "var defaultMaximumTruncationLength = " new_length ";")}1' "$file_path" > temp_file && mv temp_file "$file_path"

echo "Length updated successfully: "
cat "$file_path" | grep "defaultMaximumTruncationLength = "

I just wanted to call out that if your VSCode config specifies the "typescript.tsdk" option, you’ll need to update the tsserver.ts in whatever location that option specifies. It would have saved me a bit of debugging time 🙃

Thank you for saying this because you saved me a lot of time! Slight correction, though: it’s named tsserver.js

If for nothing else, I thought this was worth reporting for the irony: in my case, the ... was truncating a three character number.

@vensauro That extension doesn’t seem to work anymore. Shame, because it looks really useful.

noErrorTruncation also does not solve this problem for me.

Thanks for the hack @Hati-, Another gotcha I found is that if you’re using VSCode on the WSL2, your tsserver.js is located here:

~/.vscode-server/bin/*SOME_HASH_HERE*/extensions/node_modules/typescript/lib/tsserver.js

Here’s a quick bash script I use to quickly switch back and forth to avoid any performance issues with high values on the truncation:

#!/bin/bash

if [ $# -lt 1 ]; then
  echo "Usage: $0 <directory_path> <new_length>?"
  exit 1
fi

directory_path="$1"
new_length="$2"

if [ -z "$2" ]
  then
    echo "No length supplied, will use default (160)"
    new_length=160
fi

file_path=$(find "$directory_path" -name "tsserver.js" 2>/dev/null)
if [ -z "$file_path" ]; then
  echo "tsserver.js file not found within directory $file_path after recursive search"
  exit 1
fi

echo "Found tsserver.js at \"$file_path\""

sed -i "s/var defaultMaximumTruncationLength = [0-9]\+;/var defaultMaximumTruncationLength = $new_length;/" "$file_path"

echo "Length updated successfully: "
cat $file_path | grep "defaultMaximumTruncationLength = "

Executing it with just the dir will result in resetting it to the default value of 160:

changeTypescriptHintLength.sh ~/.vscode-server

Executing it with a second argument will change it

changeTypescriptHintLength.sh ~/.vscode-server 800

Note: restarting the TS server is enough for the changes to take effect, no need to restart the entire VSCode.