When comparing React Native vs NativeScript, the Slant community recommends React Native for most people. In the question“What are the best frameworks for developing cross-platform mobile apps?” React Native is ranked 3rd while NativeScript is ranked 9th. The most important reason people chose React Native is:
React Native allows you to create native apps by generating native views with JavaScript instead of using a web wrapper.
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Pros
Pro Allows you to develop native apps
React Native allows you to create native apps by generating native views with JavaScript instead of using a web wrapper.
Pro Large, supportive community
Despite being such a young framework (early 2015), the support for React Native grew quickly. There is a forum, active tag on Stackoverflow and many other ways to get help from the community.

Pro Backed by Facebook
Facebook writes their mobile apps in React Native so the code base gets pretty thoroughly used in some highly demanding scenarios.
Pro More predictable control of the state
The one way data flow, makes it more predictable and easy to control.
Pro Svelte Native
Used by Svelte framework for native development.
Pro Leverages knowledge in Angular
Angular is a very popular framework, and teams already developing angular will feel right at home with Nativescript + Angular
Pro Works great with vue.js
Cons
Con If core team doesn't use a certain feature, it's not developed
Whenever there's functionality you need that they don't use in their apps, it's not going to get developed by them, even if it's obvious it should be in the core. They always say to either submit a PR or create a separate module.
Con Steep learning curve
React Native is not the most beginner-friendly framework for creating mobile apps with JavaScript. It requires that the developer know React, which is known to have a steep learning curve.
Con Many existing JS libraries are not usable on React Native; not exactly a 1-to-1 experience to writing React either
Example: Library that provides a full calendar with agenda view.
In the end it's much easier to develop in actual JavaScript with a solution such as Ionic, especially if your app needs to work well on the desktop.
Con React native only supports react which is getting old
React native is only based on react which is getting old. An old tech developer can't take much breaking changes so it gets more patchs. There is a limit, and react is too verbose and complex. better alternatives available today.
Con Nativescript + Angular apps for Android tend to have long startup times.
It's very difficult to have acceptable startup times with NS+Angular in Android. It's not uncommon to see apps taking 6 sec or more to start AFTER having been optimized with Webpack (mandatory!). The same app in iOS takes only 2-3 sec. Also, this seems to happen only with the NS+Angular flavour. People using plain NS (without Angular) don't seem to have the issue.
