Skip to main content

TypeScript 4.2 comes with smarter type alias preservation

Microsoft has announced the official release of TypeScript 4.2, the latest version of its JavaScript superset programming language.

There are a number of new features in this release, including smarter type alias preservation, leading/middle rest elements in tuple types, and stricter checks for the “in” operator. 

Type aliases can be used to avoid having to repeat functions that work for a number of different types, such as strings, numbers, and booleans. An issue arises when TypeScript tries to normalize union types into a flattened union type, which results in information loss, thus forcing the type-checker to search for every combination of types to see what type aliases might have been used. This release improves the internals around type aliases to keep track of how types were constructed and enable types to be printed the way they were used in the code. 

Another new change in TypeScript 4.2 is an expansion to how rest elements can be used. Previously they could only be used in the last position of a tuple type, but now they can be used anywhere within a tuple. The one exception is that it can’t be followed by another optional element or rest element. 

TypeScript 4.2 also provides stricter checks for the “in” operator. Using a non-object type on the right side of the “in” operator throws a runtime error in JavaScript, so this change will help to ensure that these issues are caught during the development process. 

Other new features in TypeScript 4.2 include –noPropertyAccessFromIndexSignature, abstract construct signatures, the –explainFiles flag, improved uncalled function checks in logical expressions, destructured variables that can be explicitly marked as unused, relaxed rules between optional properties and string index signatures, and the ability to declare new functions and methods based on the call-site. 

The TypeScript team is also already working on version 4.3 and expects to release the first beta on March 30 and the final release on May 25.  

The post TypeScript 4.2 comes with smarter type alias preservation appeared first on SD Times.



from SD Times https://ift.tt/37F0jdl
Labels:

Comments

Post a Comment

Popular posts from this blog

Difference between Web Designer and Web Developer Neeraj Mishra The Crazy Programmer

Have you ever wondered about the distinctions between web developers’ and web designers’ duties and obligations? You’re not alone! Many people have trouble distinguishing between these two. Although they collaborate to publish new websites on the internet, web developers and web designers play very different roles. To put these job possibilities into perspective, consider the construction of a house. To create a vision for the house, including the visual components, the space planning and layout, the materials, and the overall appearance and sense of the space, you need an architect. That said, to translate an idea into a building, you need construction professionals to take those architectural drawings and put them into practice. Image Source In a similar vein, web development and design work together to create websites. Let’s examine the major responsibilities and distinctions between web developers and web designers. Let’s get going, shall we? What Does a Web Designer Do?
Post a Comment
Read more

A guide to data integration tools

CData Software is a leader in data access and connectivity solutions. It specializes in the development of data drivers and data access technologies for real-time access to online or on-premise applications, databases and web APIs. The company is focused on bringing data connectivity capabilities natively into tools organizations already use. It also features ETL/ELT solutions, enterprise connectors, and data visualization. Matillion ’s data transformation software empowers customers to extract data from a wide number of sources, load it into their chosen cloud data warehouse (CDW) and transform that data from its siloed source state, into analytics-ready insights – prepared for advanced analytics, machine learning, and artificial intelligence use cases. Only Matillion is purpose-built for Snowflake, Amazon Redshift, Google BigQuery, and Microsoft Azure, enabling businesses to achieve new levels of simplicity, speed, scale, and savings. Trusted by companies of all sizes to meet
Post a Comment
Read more

2022: The year of hybrid work

Remote work was once considered a luxury to many, but in 2020, it became a necessity for a large portion of the workforce, as the scary and unknown COVID-19 virus sickened and even took the lives of so many people around the world.  Some workers were able to thrive in a remote setting, while others felt isolated and struggled to keep up a balance between their work and home lives. Last year saw the availability of life-saving vaccines, so companies were able to start having the conversation about what to do next. Should they keep everyone remote? Should they go back to working in the office full time? Or should they do something in between? Enter hybrid work, which offers a mix of the two. A Fall 2021 study conducted by Google revealed that over 75% of survey respondents expect hybrid work to become a standard practice within their organization within the next three years.  Thus, two years after the world abruptly shifted to widespread adoption of remote work, we are declaring 20
Post a Comment
Read more