TypeScript Continues Embrace of React Native
TypeScript began supporting JSX back in September 2015 in version 1.6. "Our goal was to make it feel natural to work with React/JSX and to have all the type-checking and autocomplete capabilities of TypeScript," Microsoft said at the time. "This allows you a rich editing experience for working with React and JSX when using VS, VS Code, and Sublime."
Since then, JSX support has been steadily expanded, and the TypeScript 2.2 RC adds yet more JSX functionality in the form of a new way to emit JSX code.
Here's Microsoft's description of that new emit mode, as presented in a blog post:
In TypeScript 2.1 and earlier, the --jsx flag could take on two values:
TypeScript 2.2 has a new JSX emit mode called react-native which sits somewhere in the middle. Under this scheme, JSX syntax is left alone, but generates .js files.
- preserve which leaves JSX syntax alone and generates .jsx files.
- react which transforms JSX into calls to React.createElement and generates .js files.
This new mode accomodates React Native's loader which expects all input files to be .js files. It also satisfies cases where you want to just leave your JSX syntax alone but get .js files out from TypeScript.
Another new feature in TypeScript. 2.2 is the introduction of an
object primitive type (as opposed to a capitalized
Object that has a whole different meaning). It provides more flexibility in supplying values for certain APIs, such as in the
Object.create() method, which requires a non-primitive first argument. Microsoft said it will help catch more bugs "and more accurately model real world code."
Yet another new feature in v2.2 highlighted in Microsoft's blog post is improved support for mixins and composable classes. Those and other features that weren't mentioned in the blog post can be seen in the TypeScript Roadmap. It shows TypeScript 2.3, due in May, will continue to expand support for React Native/JSX by providing "better support for literal types in JSX attributes."
npm install -g typescript@rc command.
"You can also get the TypeScript release candidate for Visual Studio 2015 (if you have Update 3)," Microsoft said. "Other built-in editor support will be coming with our proper 2.2 release, but you can look at guides on how to enable newer versions of TypeScript in Visual Studio Code and Sublime Text 3."
David Ramel is the editor of Visual Studio Magazine.