In Javascript, `typeof x !== undefined ? t : f` should act like a declaration of `x` in the true branch

**Search Terms:** existence of define typeof undefined **Code** ```ts // @noEmit: true // @allowJs: true // @checkJs: true // @strict: true // @Filename: a.js if (typeof define !== 'undefined' && define.amd) { define([], function() { }) } // also, nested exports.storage = 'undefined' != typeof chrome && 'undefined' != typeof chrome.storage ? chrome.storage.local : undefined; ``` **Expected behavior:** The check `type define !== undefined` should cause the true branch of the conditional to act as if `define` were declared. **Actual behavior:** Cannot find name 'define'.