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70 posts tagged with "TypeScript"

The TypeScript programming language.

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ESLint no-unused-vars: _ ignore prefix

· 6 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

I'm a longtime user of TypeScripts noUnusedLocals and noUnusedParameters settings. I like to avoid leaving unused variables in my code; these compiler options help me do that.

I use ESLint alongside TypeScript. The no-unused-vars rule provides similar functionality to TypeScripts noUnusedLocals and noUnusedParameters settings, but has more power and more flexibility. For instance, no-unused-vars can catch unused error variables; TypeScript's noUnusedLocals and noUnusedParameters cannot.

One thing that I missed when switching to the ESLint option is that, with noUnusedLocals and noUnusedParameters, you can simply ignore unused variables by prefixing a variable with the _ character. That's right, sometimes I want to declare a variable that I know I'm not going to use, and I want to do that without getting shouted at by the linter.

It turns out you can get ESLint to respect the TypeScript default of ignoring variables prefixed with _; it's just not the default configuration for no-unused-vars. But with a little configuration we can have it. This post is a quick guide to how to implement that configuration.

title image reading "From TypeScript noUnusedLocals and noUnusedParameters to ESLint no-unused-vars (with _ prefix)" with the ESLint and TypeScript logo

Migrating to v4 Azure Functions Node.js with TypeScript

· 9 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

There's a new programming model available for Node.js Azure Functions known as v4. There's documentation out there for how to migrate JavaScript Azure Functions from v3 to v4, but at the time of writing, TypeScript wasn't covered.

This post fills in the gaps for a TypeScript Azure Function. It's probably worth mentioning that my blog is an Azure Static Web App with a TypeScript Node.js Azure Functions back end. So, this post is based on my experience migrating my blog to v4.

title image reading "Link Azure Application Insights to Static Web Apps with Bicep" with the Bicep and Azure Static Web App logos

Azure Open AI: generate article metadata with TypeScript

· 10 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

This post grew out of my desire to improve the metadata for my blog posts. I have been blogging for more than ten years, and the majority of my posts lack descriptions. A description is meta tag that sits in a page and describes the contents of the page. This is what this posts description meta tag looks like in HTML:

<meta
name="description"
content="Use the TypeScript Azure Open AI SDK to generate article metadata."
/>

Descriptions are important for search engine optimisation (SEO) and for accessibility. You can read up more on the topic here. I wanted to have descriptions for all my blog posts. But writing around 230 descriptions for my existing posts was not something I wanted to do manually. I wanted to automate it.

title image reading &quot;Azure Open AI: generate article metadata with TypeScript&quot; with the Azure Open AI / TypeScript logos

TypeScript: The Movie

· One min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

I am excited to announce that a documentary has been made about TypeScript! It premiered on YouTube at 5pm British Summertime September 21st 2023.

I had the good fortune to be involved in the making of the documentary. In part this was thanks to my work on Definitely Typed. Another reason was my work on recording the history of DefinitelyTyped.

You can see it on YouTube here or hit play on the embedded video above. Thanks to the Keyboard Stories team for making this happen!

TypeScript 5.1: declaring JSX element types

· 6 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

A new feature arrives with TypeScript 5.1, it is described as "Decoupled Type-Checking Between JSX Elements and JSX Tag Types".

It's all about handing control of JSX type definitions to libraries. With this feature, libraries can control what types are used for JSX elements. Why does this matter? Great question! Until version 5.1, TypeScript did an imperfect job of representing what is possible with JSX. This feature allows libraries to do a better job of that, and we'll look into it in this post.

It's probably worth saying, that this is a complicated feature. If you don't understand it (and as the author of this post I'll confess that I had to work quite hard to understand it), that is okay. This is a low level feature that is only likely to be used by library / type definition authors. It's a primitive that will unlock possibilites for people writing JSX - but it's something that people will mainly feel the benefit of, without directly doing anything themselves, or necessarily noticing that things have changed for the better.

title image reading &quot;TypeScript 5.1: declaring JSX element types&quot; with the TypeScript logo

TypeScript 5: importsNotUsedAsValues replaced by ESLint consistent-type-imports

· 7 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

I really like type imports that are unambiguous. For this reason, I've made use of the "importsNotUsedAsValues": "error" option in tsconfig.json for a while now. This option has been deprecated in TypeScript 5.0.0, and will be removed in TypeScript 5.5.0. This post will look at what you can do instead.

title image reading &quot;TypeScript 5: importsNotUsedAsValues replaced by ESLint consistent-type-imports&quot; with the ESLint and TypeScript logo

Migrating from ts-node to Bun

· 10 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

I've wanted to take a look at some of the alternative JavaScript runtimes for a while. The thing that has held me back is npm compatibility. I want to be able to run my code in a runtime that isn't Node.js and still be able to use npm packages. I've been using ts-node for a long time now; it's what I reach for when I'm building any kind of console app. In this post I want to port a console app from ts-node to Bun and see how easy it is.

title image reading &quot;From ts-node to Bun&quot;

Type annotations: strong types, weakly held

· 9 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

Recently, a new ECMAScript proposal called "Type Annotations" (originally named "Types as Comments") was revealed. The purpose is to allow type annotations to be valid JavaScript syntax. Albeit syntax that is ignored by JavaScript engines. The proposal is being worked on by Gil Tayar, Daniel Rosenwasser, Romulo Cintra, Rob Palmer, and others. Many of these people are from TypeScript community - however this proposal intentionally does not exist to benefit TypeScript alone.

TypeScript vs JSDoc JavaScript

· 6 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

There's a debate to be had about whether using JavaScript or TypeScript leads to better outcomes when building a project. The introduction of using JSDoc annotations to type a JavaScript codebase introduces a new dynamic to this discussion. This post will investigate what that looks like, and come to an (opinionated) conclusion.

title image reading &quot;JSDoc JavaScript vs TypeScript&quot; with a JavaScript logo and TypeScript logo

Google APIs: authentication with TypeScript

· 9 min read
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

Google has a wealth of APIs which we can interact with. At the time of writing, there's more than two hundred available; including YouTube, Google Calendar and GMail (alongside many others). To integrate with these APIs, it's necessary to authenticate and then use that credential with the API. This post will take you through how to do just that using TypeScript. It will also demonstrate how to use one of those APIs: the Google Calendar API.