WebConstruction with an array will create a date in the current time zone. The same checking works with switch statements as well. Actually, I have already created such a custom transformer, which enables the following. did anything serious ever run on the speccy? Now the only warnings that npm run check emits are triggered by calling the Todo.svelte component. For example, to remove an item from myArray, construct a new array: this. We'll take care of them properly later on. const values = myArray.map(obj => obj.value); This call back function will return a new array containing only values from the original array and store it on values const. Update the import statement in stores.ts like so: Now if we try to create a localStore with something that cannot be converted to JSON via JSON.stringify(), for example an object with a function as a property, VS Code/validate will complain about it: And best of all, it will even work with the $store auto-subscription syntax. / I get an "implicitly has type 'any' error". You might also be running some intermediate steps on your JavaScript, such as bundling or using another transpiler like Babel. If you open that file in an editor with TypeScript support (or if you run tsc --pretty), you might see red squiggles on certain lines. Share. If we pass an unknown property in the options parameter of the App constructor (for example a typo like traget instead of target), TypeScript will complain: In the App.svelte component, the setupTypeScript.js script has added the lang="ts" attribute to the