TypeScript (https://en.wikipedia.org/wiki/TypeScript) is a language that compiles down to JavaScript.
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Starting with version 5.5, Tapestry can automatically compile your TypeScript code into JavaScript on the fly. This is done with the optional tapestry-webresources module. It is highly recommended for anyone who wants to use TypeScript in their application ... just let Tapestry do the compilation at runtime (with access to Tapestry's full exception reporting capabilities).
To use the tapestry-webresources module, just add the JAR to your project. For example, if you're using Maven:
pom.xml (partial)
<dependency>
<groupId>org.apache.tapestry</groupId>
<artifactId>tapestry-webresources</artifactId>
<version>${tapestry-release-version}</version>
</dependency>