René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Optional local variables","articleBody":"## Suggestion\r\n\r\nTypeScript already supports optional parameters and fields with a question mark.\r\nWhy not extend this feature to local variables as well, to allow them having an undefined value, e.g.\r\n\r\n## Use Cases/Examples\r\n\r\n```\r\nlet optional?: number = 123\r\noptional = undefined // allowed\r\n```\r\n\r\nin this case specifying `number` type is also optional:\r\n\r\n```\r\nlet optional? = 123\r\n```\r\n\r\nThis would complete the usage of question mark `?` as nullablity/unefineability operator, similar to Kotlin.\r\n\r\nCurrently, defining an optional variable requires writing a lot of noise, e.g.\r\n\r\n```\r\nlet optional: number|undefined = undefined  // too verbose\r\n```\r\n\r\n## Checklist\r\n\r\nMy suggestion meets these guidelines:\r\n\r\n* [x] This wouldn't be a breaking change in existing TypeScript/JavaScript code\r\n* [x] This wouldn't change the runtime behavior of existing JavaScript code\r\n* [x] This could be implemented without emitting different JS based on the types of the expressions\r\n* [x] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)\r\n* [x] This feature would agree with the rest of [TypeScript's Design Goals](https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals).\r\n","author":{"url":"https://github.com/angryziber","@type":"Person","name":"angryziber"},"datePublished":"2020-12-09T19:31:10.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/41901/TypeScript/issues/41901"}