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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Lib files leak \"support\" types into global namespace","articleBody":"\u003c!-- BUGS: Please use this template. --\u003e\r\n\u003c!-- QUESTIONS: This is not a general support forum! Ask Qs at http://stackoverflow.com/questions/tagged/typescript --\u003e\r\n\u003c!-- SUGGESTIONS: See https://github.com/Microsoft/TypeScript-wiki/blob/master/Writing-Good-Design-Proposals.md --\u003e\r\n**TypeScript Version:**  2.2.1 / nightly (2.2.0-dev.201xxxxx)\r\n# Description\r\nCore ECMAScript lib declaration files (e.g. [lib.es5.d.ts](https://github.com/Microsoft/TypeScript/blob/master/lib/lib.es5.d.ts)) leak \"internal\" interface types into the global namespace. A common pattern employed in the lib files is that \"class\"-static features are placed in a `[TypeName]Constructor` interface and then a `const` variable of that type is declared with the same TypeName as the `[TypeName]` interface. Example:\r\n\r\n```ts\r\ninterface Object {\r\n    constructor: Function;\r\n    // ...\r\n}\r\n\r\ninterface ObjectConstructor {\r\n    new (value?: any): Object;\r\n    (): any;\r\n    (value: any): any;\r\n    // ...\r\n}\r\n\r\ndeclare const Object: ObjectConstructor;\r\n```\r\nThe problem is that the `ObjectConstructor` type is leaked into the global namespace. No such type is defined in the [ECMAScript 5.1 language spec](https://www.ecma-international.org/ecma-262/5.1/index.html), and yet it clutters up auto-complete suggestions.\r\n\r\nThe `[TypeName]Constructor` pattern seems like a workaround to enable certain features to be expressed in the lib files. The leaking of these types seems to be a side-effect of this construction.\r\n\r\n# Expected Behavior\r\nIncluding a core ECMAScript lib file into a project (whether by default or compilerOption) only adds types found in the associated ECMAScript specifications into the global namespace.\r\n\r\n# Actual Behavior\r\n`[TypeName]Constructor` types end up in the global namespace for any project that includes a library utilizing such a pattern.","author":{"url":"https://github.com/ericdrobinson","@type":"Person","name":"ericdrobinson"},"datePublished":"2017-05-02T15:54:27.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":11},"url":"https://github.com/15529/TypeScript/issues/15529"}