Microsoft/TypeScript

Improve errors for potential arrow functions

Open

#25,898 opened on Jul 24, 2018

View on GitHub
 (1 comment) (0 reactions) (0 assignees)TypeScript (6,726 forks)batch import
BugDomain: Error MessagesEffort: ModerateHelp Wanted

Repository metrics

Stars
 (48,455 stars)
PR merge metrics
 (Avg merge 6d 17h) (9 merged PRs in 30d)

Description

There are certain locations where arrow functions don't parse

var x = window.foo || () => {}

In these instances, it would be nice if users could get a better error message as to avoid issues like #25897.

Ideally this should not be an invasive change.

  • The change should be limited in scope.
  • The parser should continue erroring in those locations.
  • The change must not introduce change how existing valid code is parsed.

Contributor guide

Research direction
Examine the parser in `src/compiler/parser.ts` for locations where arrow functions are rejected and enhance error messages to hint at potential arrow function syntax issues. Look at related issues like #25897 for context.
Tech stack
typescript
Domain
compilers
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
TypeScriptGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60