Microsoft/TypeScript

Assignments to global objects in Javascript should be global declarations

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#22,446 opened on Mar 9, 2018

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 (3 comments) (0 reactions) (0 assignees)TypeScript (6,726 forks)batch import
BugDomain: JavaScriptEffort: ModerateExperience EnhancementHelp WantedRescheduled

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Description

// @noEmit: true
// @allowJs: true
// @checkJs: true
// @Filename: a.js
global.x = 1
window.y = 2
this.z = 3

var n = x + y + z

Expected behavior: No error, and x, y and z are visible globally.

Actual behavior: Errors:

  1. Can't find name 'global'
  2. 'Window' has no property 'y'
  3. Cannot find name 'x', 'y' or 'z'

Ideally, global should only be visible when targetting node and window should only be visible when targetting the browser. It's not a requirement, though.

Contributor guide

Research direction
Examine how TypeScript handles global variables and the lib definitions for window and global. Look at the checker's handling of property assignments on global objects to understand why errors are produced and how to treat them as global declarations.
Tech stack
typescript
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
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.
Clear
Prerequisites
GitJavaScriptTypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60