Writing your stories in TypeScript makes you more productive. You don't have to jump between files to look up component props. Your code editor will alert you about missing required props and even autocomplete prop values, just like when using your components within your app. Plus, Storybook infers those component types to auto-generate the Controls table.
Storybook has built-in TypeScript support, so you can get started with zero configuration required.
Typing stories with Meta and StoryObj
When writing stories, there are two aspects that are helpful to type. The first is the component meta, which describes and configures the component and its stories. In a CSF file, this is the default export. The second is the stories themselves.
Storybook provides utility types for each of these, named Meta and StoryObj. Here's an example CSF file using those types:
Props type parameter
Meta and StoryObj types are both generics, so you can provide them with an optional prop type parameter for the component type or the component's props type (e.g., the typeof Button portion of Meta<typeof Button>). By doing so, TypeScript will prevent you from defining an invalid arg, and all decorators, play functions, or loaders will type their function arguments.
The example above passes a component type. See Typing custom args for an example of passing a props type.
Using satisfies for better type safety
If you are using TypeScript 4.9+, you can take advantage of the new satisfies operator to get stricter type checking. Now you will receive type errors for missing required args, not just invalid ones.
Using satisfies to apply a story's type helps maintain type safety when sharing a play function across stories. Without it, TypeScript will throw an error that the play function may be undefined. The satisfies operator enables TypeScript to infer whether the play function is defined or not.
Finally, use of satisfies allows you to pass typeof meta to the StoryObj generic. This informs TypeScript of the connection between the meta and StoryObj types, which allows it to infer the args type from the meta type. In other words, TypeScript will understand that args can be defined both at the story and meta level and won't throw an error when a required arg is defined at the meta level, but not at the story level.
Typing custom args
Sometimes stories need to define args that aren’t included in the component's props. For this case, you can use an intersection type to combine a component's props type and your custom args' type. For example, here's how you could use a footer arg to populate a child component: