JSweet vs Scala.js
JSweet
jsweet.org
Scala.js
scala-js.orgSide by side
| Figure | JSweet | Scala.js |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | Yes | — |
| Web | Yes | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| iOS | Yes | — |
| Android | Yes | — |
| API | Yes | Yes |
| Self-hosted | Yes | — |
| Plans published | 1 | 1 |
| Spec score · Code Transpilers | 8.7 (#1) | 7.6 (#19) |
| JavaScript interoperability | Generated output is ordinary JavaScript intended to interoperate directly with JavaScript code and libraries. | Scala.js can use JavaScript libraries and interact with JavaScript APIs, with either statically or dynamically typed access. |
| Library ecosystem | The project advertises more than 1,000 JavaScript libraries, frameworks and plugins through JSweet bindings. | The libraries page lists facades and integrations for libraries including React, Angular, Vue, Three.js, and Chart.js. |
| License | The repository links to a license file but the opened page does not state the license name in its displayed README text. | The project repository states that Scala.js is distributed under the Apache License Version 2.0. |
Plans
In their own words
JSweet
JSweet converts Java programs into TypeScript and JavaScript for browsers, mobile Web views, or Node.js. It uses Oracle's Java compiler alongside Microsoft's TypeScript compiler to generate type-checked JavaScript. The project describes the output as regular JavaScript that can work directly with JavaScript programs and libraries. Listed language features include Java-to-TypeScript syntax mapping, Java constructs, async/await, and ECMAScript targets from ES3 to ES6. JSweet lists support for more than 1,000 JavaScript libraries, frameworks, and plugins, packaged as Maven artifacts called candies. It provides Eclipse, Maven, and Gradle plugins, and names Angular, Cordova, Node.js, and Three.js among example integrations. Generated programs can use CommonJS, AMD, or UMD modules and run in browsers or Node.js. A debug mode supports debugging Java code in a browser. Setup instructions call for Git, Node.js, and Maven, then use Maven to generate JavaScript from a quickstart project. JSweet is open source and free, and is presented for Java developers building web and mobile HTML5 applications with JavaScript libraries and frameworks.
Scala.js
Scala.js is a Scala-to-JavaScript compiler for building applications that run in browsers, Node.js, and serverless environments. The project also states that WebAssembly support is stable. Scala's strong typing can catch mistakes such as mixing strings and numbers or using misspelled method names, while editor support can flag type errors and show inline details about methods, arguments, return types, and documentation. The project describes incremental compilation with a 1–2 second turnaround; generated JavaScript for a full application starts at 45 kB gzipped. Scala.js can use JavaScript libraries and APIs through statically or dynamically typed access. Listed library integrations include React, Angular, Vue, Three.js, and Chart.js. Build tool options include sbt, scala-cli, Mill, and Gradle with a Scala.js plugin. Tutorials list Scala development tools and Node.js as prerequisites and recommend VS Code with Metals. Scala.js is free and distributed under the Apache License 2.0. Documentation points users to community support through Discord and Stack Overflow. The 1.22.0 release is not entirely backward source compatible with 1.21.x.