TypeScript 3.4 is out: Microsoft tweaks programming language to cut build times

The latest version of the TypeScript programming language promises to cut compile times for existing projects.
Written by Liam Tung, Contributing Writer

Microsoft has released TypeScript 3.4, a language that's growing among developers and helping them scale up projects written in today's top coding language, JavaScript. 

Released in 2012, TypeScript looks set to become a mainstay among the world's top programming languages, lying just outside top 10 status in one ranking based on projects in GitHub and chatter on Stack Overflow. 

TypeScript, which compiles to plain JavaScript, offers developers a compiler with safety features that check programs based on optional static types – like strings, arrays, text, and numbers – to catch errors and to clean up JavaScript code. 

Also, as a language server, it can be used for cross-platform editor tooling, such as code completions, fixes, and refactoring. Meanwhile, JavaScript developers can use it to type-check, or verify, JavaScript code.  

TypeScript 3.4's headline feature is a new flag called 'incremental', which aims to help developers type-check and output changes to an existing project, allowing them to save time when compiling subsequent builds.   

The flag "tells TypeScript to save information about the project graph from the last compilation", explains Daniel Rosenwasser, program manager on the TypeScript team. 

"The next time TypeScript is invoked with --incremental, it will use that information to detect the least costly way to type-check and emit changes to your project."

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Rosenwasser boasts that adding the new flag to a TypeScript file for Microsoft's Visual Studio Code editor drastically cut compile time for follow-on builds. 

"For a project the size of Visual Studio Code, TypeScript's new --incremental flag was able to reduce subsequent build times down to approximately a fifth of the original," he notes. 

Currently TypeScript editor support is available in Visual Studio and Visual Studio Code when using it as an editor for JavaScript files.

However, Rosenwasser notes that it is likely to come "in the near future" to other popular editors such as EMACS, NetBeans, Notepad++, and Vim.

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