Microsoft/TypeScript

Constructor function in JS not recognized when it's a property of an object literal

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#52,885 opened on Feb 15, 2023

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 (4 comments) (0 reactions) (0 assignees)TypeScript (48,455 stars) (6,726 forks)batch import
BugDomain: JavaScriptHelp Wanted

Description

TS Template added by @mjbvz

TypeScript Version: 5.0.1

Search Terms

  • parameter hints
  • signature help

Type: Bug

The problem is that suggested object parameters do not appear anymore when using the keyword New to initialize a new object, illustrated below.

var test = { best: function(west){ this.west = west; } }; new test.best()

VS Code version: Code 1.75.0 (e2816fe719a4026ffa1ee0189dc89bdfdbafb164, 2023-02-01T15:23:45.584Z) OS version: Windows_NT x64 10.0.22621 Modes: Sandboxed: No

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Load (avg) undefined
Memory (System) 15.69GB (4.19GB free)
Process Argv --crash-reporter-id 30548cfd-b06a-4b29-85b3-53e6455ac4b3
Screen Reader no
VM 0%
Extension Author (truncated) Version
csharp ms- 1.25.4
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Contributor guide

Tech stack
typescriptjavascript
Domain
developer experience
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic TypeScript knowledgeUnderstanding of constructor functions
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate how TypeScript's signature help resolves constructor call expressions when the constructor is a property of an object literal. The issue is that `new test.best()` does not show parameter hints for the `best` function. Look into the `signatureHelp` feature (likely in `src/services/signatureHelp.ts`) and how the type checker handles `new` expressions on computed property types. Check if there is a missing resolution for method signatures in object literals when called with `new`. Consider the TypeScript compiler's handling of construct signatures vs call signatures.