TypeScript and JavaScript are the two most popular scripting languages in current project development. We already know that TypeScript is a superset of JavaScript, but what is the difference between TypeScript and JavaScript? When choosing a development language, how should you choose?
This article will compare the two languages in depth, discuss the relatedness and differences between the two languages, and outline their respective strengths.
A high-level introduction to JavaScript and TypeScript
JavaScript
JavaScript is a lightweight interpreted scripting language that can be embedded in HTML pages and executed on the browser side. It can realize rich interactive functions on the browser side and bring users a smooth and diverse user experience.
JavaScript is object-based and event-driven, requires no specific locale, and simply runs on supported browsers.
The JavaScript language has the following characteristics:
- JavaScript is a scripting language that does not need to be compiled. As long as it is embedded in the HTML code, it can be loaded, interpreted and executed by the browser line by line.
- JavaScript is an object-based language that can create objects while using existing objects. But Javascript does not support inheritance and overloading that other object-oriented languages have.
- The syntax of JavaScript is simple and the variables used are weakly typed.
- The JavaScript language is relatively safe, only executed on the browser side, and will not access local hard disk data.
- The JavaScript language is dynamic. JavaScript is event-driven and only reacts to user actions.
- JavaScript only depends on the browser and has nothing to do with the operating system. So JavaScript is a cross-platform language.
- JavaScript is compatible and can be used with other technologies such as XML, REST API, etc.
TypeScript
TypeScript is an object-oriented programming language developed and maintained by Microsoft. It is a superset of JavaScript, including all the elements of JavaScript, you can load JavaScript code to run, and extend the syntax of JavaScript.
TypeScript has the following characteristics:
- TypeScript is an open source language launched by Microsoft and uses the Apache license
- TypeScript adds static typing, classes, modules, interfaces and type annotations
- TypeScript can be used to develop large applications
- TypeScript is easy to learn and understand
Main differences between JavaScript and TypeScript
TypeScript can use all the code and coding concepts in JavaScript, TypeScript was created to make JavaScript development easier. For example, TypeScript uses concepts like types and interfaces to describe the data being used, which enables developers to quickly detect errors and debug applications
- TypeScript extends the JavaScript object model in terms of the core language and the modeling of class concepts.
- JavaScript code can work with TypeScript without any modification, and a compiler can be used to convert TypeScript code to JavaScript.
- TypeScript provides compile-time static type checking through type annotations.
- Data in TypeScript requires an explicit type, JavaScript does not.
- TypeScript provides default parameter values for functions.
- TypeScript introduces the concept of "classes" not found in JavaScript.
- TypeScript introduces the concept of modules, which can encapsulate declarations, data, functions, and classes in modules.
Advantages of TypeScript
Listed below are the significant advantages of TypeScript over JavaScript:
1. Static input
静态类型化是一种功能，可以在开发人员编写脚本时检测错误。查找并修复错误是当今开发团队的迫切需求。有了这项功能，就会允许开发人员编写更健壮的代码并对其进行维护，以便使得代码质量更好、更清晰。
2. 大型的开发项目
有时为了改进开发项目，需要对代码库进行小的增量更改。这些小小的变化可能会产生严重的、意想不到的后果，因此有必要撤销这些变化。使用TypeScript工具来进行重构更变的容易、快捷。
3. 更好的协作
当发开大型项目时，会有许多开发人员，此时乱码和错误的机也会增加。类型安全是一种在编码期间检测错误的功能，而不是在编译项目时检测错误。这为开发团队创建了一个更高效的编码和调试过程。
4. 更强的生产力
干净的 ECMAScript 6 代码，自动完成和动态输入等因素有助于提高开发人员的工作效率。这些功能也有助于编译器创建优化的代码。
JavaScript 的优势
相比于 TypeScript，JavaScript 也有一些明显优势。
1. 人气
JavaScript 的开发者社区仍然是巨大而活跃的，在社区中可以很方便地找到大量成熟的开发项目和可用资源。
2. 学习曲线
由于 JavaScript 语言发展的较早，也较为成熟，所以仍有一大批开发人员坚持使用他们熟悉的脚本语言 JavaScript，而不是学习 TypeScript。
3. 本地浏览器支持
TypeScript 代码需要被编译（输出 JavaScript 代码），这是 TypeScript 代码执行时的一个额外的步骤。
4. 不需要注释
为了充分利用 TypeScript 特性，开发人员需要不断注释他们的代码，这可能会使项目效率降低。
5. 灵活性
有些开发人员更喜欢 JavaScript 的灵活性。
如何抉择
TypeScript 正在成为开发大型编码项目的有力工具。因为其面向对象编程语言的结构保持了代码的清洁、一致和简单的调试。因此在应对大型开发项目时，使用 TypeScript 更加合适。如果有一个相对较小的编码项目，似乎没有必要使用 TypeScript，只需使用灵活的 JavaScript 即可。
JavaScript 开发工具推荐
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参考文章：https://dzone.com/articles/typescript-vs-javascript-should-you-migrate-your-j
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