What's new in Angular 4.3?

Angular 4.3.0 is here!

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This is a fairly big release, with a new HttpClientModule, a complete rewrite of the HttpModule 💅! This should be the last minor release before Angular 5, when we can expect some other exciting stuff!


The biggest feature of this release is without a doubt the new HttpClientModule. This module is a complete rewrite of the current HttpModule that had some defaults, like the obligation to extract the JSON from the response for every request, no mechanism to handle requests and responses in a generic fashion, and a quite awful testing API.

The new HttpClientModule is a really cool alternative: it solves all these issues, and we migrated our applications fairly easily. And it was mostly code deletions 💖.

We made a little video to show you the difference, and a complete article to help you to migrate your applications.

It showcases the brand new HttpClient service, how to write unit tests, and how to use the new interceptors!

Check out the article we wrote that explains in deep how to use this new module!


A few events have been added to the router, if you need to know when a resolver or a guard is run:

  • ResolveStart, ResolveEnd
  • GuardsCheckStart, GuardsCheckEnd


The two new validators min and max released with 4.2 have been temporarily rolled back as they were breaking changes :(. They’ll return in a major release, probably 5.0.0.


You may know that the /deep/ “shadow-piercing” combinator can be used to force a style down to child components. This selector had an alias >>> and now has another one called ::ng-deep.

Be warned though: the /deep/ combinator has been deprecated from the Shadow DOM spec and is being removed from all major browsers. So the support will probably also be dropped by Angular in the future. Until then, it is recommended to use ::ng-deep, and to only use it with emulated view encapsulation.


This is not really a new feature, but I think it is interesting to understand how things work under the hood.

TypeScript 2.3 recently introduced the concept of transformers in the compiler API. That means some teams can write custom transformations/plugins that are applied to the code compiled by tsc. This is not really something that we common mortals will write, but Angular has its own compiler called ngc that wraps tsc.

Until now, the process for ngc was to compile your templates to generate TypeScript files, and then call tsc to compile your TypeScript code and the TypeScript files generated to JavaScript. If that sounds strange, you can check out our ebook where we explain all this.

With the introduction of transformers, tsc works slightly differently: it starts by parsing the files, does the type-checking, applies any plugin you want, and then generates JavaScript.

Based on this, ngc is now becoming a plugin called in the TypeScript compilation pipeline, rather than a wrapper of the TypeScript compiler.

As Angular developers, we can expect to have very precise type-checking in our templates, referring to the exact line of the problem in HTML source file!


That’s all for this release: the next important one will be 5.0!

In the meantime, all our materials (ebook, online training (Pro Pack) and training) are up-to-date with these changes if you want to learn more!

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