Microsoft/TypeScript

Dangerous "name" (and potentially others) global

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#18,433 创建于 2017年9月13日

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 (74 评论) (39 反应) (0 负责人)TypeScript (48,455 star) (6,726 fork)batch import
CommittedDomain: lib.d.tsGood First IssueHelp WantedSuggestion

描述

TypeScript Version: 2.6.0-dev.20170913

Code

if (name === "asdf") {
  console.log("asdf")
}

https://www.typescriptlang.org/play/#src=if (name %3D%3D%3D "asdf") {%0D%0A console.log('hello')%0D%0A}

Expected behavior:

Error out

Actual behavior:

More than once, I had a "local" variable called name, outside a block scope, and it didn't warn me that it's not defined (or used before declaration). even though, in my code, event.name is a string, the global name variable is of type never. it's defined in lib.dom.d.ts, along with other "juicy" global names that will provide some confusion, like length, external, event, closed

image

image

one 'fix' (that would be a breaking change) would to make lib.dom-globals.d.ts (the propertiers that are usually accessible through window variable) and make it an opt-in in tsconfig.json compilerOptions.lib array

贡献者指南

技术栈
typescript
领域
developer experiencetooling
议题类型
bug
难度面向新贡献者的预计实现难度，1 表示很小改动，5 表示专家级工作。
3
预计时间有经验贡献者完成调查、实现、测试并准备 pull request 的粗略时间范围。
over 1 week
活动状态议题当前的可参与程度：新鲜、活跃、陈旧、阻塞或等待维护者输入。
stale
清晰度议题是否清楚说明期望改动、验收标准和下一步。
clear
前置要求
Understanding of TypeScript's global typesKnowledge of lib.d.ts structure
新手友好度1-100 的估计分数，表示该议题对首次贡献者的友好程度。
20
研究方向
Investigate the TypeScript compiler's handling of global declarations from lib.dom.d.ts, particularly the `name` global. Review the issue comments for proposed solutions, such as making DOM globals opt in via compilerOptions.lib. Examine the source files src/compiler/checker.ts and src/lib/lib.dom.d.ts to understand how globals are defined and could be made optional.