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Basic TypeScript

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Introduction to TypeScript

TypeScript is a superset of JavaScript that adds optional static typing to the language. It was created by Microsoft with the aim of making large-scale JavaScript application development easier and less error-prone. Like JavaScript, TypeScript runs on any browser or platform that supports JavaScript.

This image shows the TypeScript logoThis image shows the TypeScript logo

TypeScript allows developers to catch errors at development time, before the code is executed. This facilitates writing safer and more maintainable code, which is especially important in large projects and development teams.

This image shows a comparison between untyped JavaScript code and typed TypeScript code, highlighting the differences in error detectionThis image shows a comparison between untyped JavaScript code and typed TypeScript code, highlighting the differences in error detection

Advantages of TypeScript

Some of the main advantages of using TypeScript include:

  • Static Typing: Allows defining data types for variables, function parameters, and return values, which helps prevent type errors.
  • IDE Enhancements: Text editors like Visual Studio Code offer autocompletion, refactoring, and real-time error detection, thanks to TypeScript.
  • JavaScript Compatibility: TypeScript is 100% compatible with JavaScript, meaning any .js file is valid TypeScript code.
  • Compile-Time Error Checking: By compiling TypeScript code to JavaScript, errors can be detected before execution.
typescript
"This code declares a variable named 'message' of type string, initializes it with the value 'Hello, world!', and then prints this value to the console."

Installing TypeScript

To start using TypeScript, it needs to be installed. One of the most common ways is to use Node.js package manager, npm. Here is how to install TypeScript globally:

bash
"This command uses npm to install TypeScript globally on the system. This allows using the tsc command, which is the TypeScript compiler, from anywhere."

Once TypeScript is installed, you can verify the installed version using the following command:

bash
"This command checks the installed version of TypeScript on your system."

First Program in TypeScript

Let's see a basic example of a TypeScript program. This program will print a greeting to the console:

typescript
"In this example, a function named greet is defined, which takes a parameter name of type string and does not return any value, as it uses the void type. Then, the function prints a personalized greeting using string template, and finally, the function is called passing the name Alice as an argument."

To compile this program, the TypeScript compiler, tsc, is used, which converts the .ts file into a JavaScript file that can be run in the browser or Node.js:

bash
"This command converts the file filename.ts to JavaScript, generating a .js file that can be executed in any JavaScript-compatible environment."

[Placeholder for image: This image shows the process of compiling a TypeScript file to JavaScript using the tsc command.]

Conclusion

In this chapter, we have explored what TypeScript is, its advantages, how to install it, and created our first basic program. In the next chapters, we will delve into data types in TypeScript and how to make the most of its capabilities to write more robust and maintainable code.

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