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Debugging Typescript

Debugging TypeScript

In this tutorial, we will be going through the basics of debugging TypeScript. Debugging is an essential part of programming and mastering it can save you a lot of time and frustration. Let's begin!

Understanding the Basics​

Before diving into the process, let's first understand what debugging is. At its most simple, debugging involves identifying and removing errors from computer hardware or software.

In TypeScript, we can encounter two kinds of errors: compile-time errors and runtime errors. Compile-time errors occur when the types in your code don't align with the TypeScript's strict typing system. Runtime errors, on the other hand, occur while the program is running.

Setting Up for Debugging​

To debug TypeScript, we'll need two things:

  1. Node.js - This is the environment where our JavaScript code will run. You can download it here.

  2. A Text Editor or IDE - This is where we'll write and debug our code. Some popular choices are Visual Studio Code, Sublime Text, and Atom. For this tutorial, we'll be using Visual Studio Code which can be downloaded here.

Debugging TypeScript in Visual Studio Code​

Visual Studio Code (VS Code) comes with a built-in debugger, which makes it a great tool for debugging TypeScript. Here's how you can debug TypeScript in VS Code:

  1. Compile TypeScript to JavaScript: Since browsers can't execute TypeScript directly, we need to compile it into JavaScript. You can do this by running the tsc command followed by the filename in your terminal. For example, tsc app.ts will compile app.ts into app.js.

  2. Configure the Debugger: To configure the debugger in VS Code, you need to create a .vscode folder in your project root, and inside it, a launch.json file. In this file, you can specify the configurations for your debugging session.

A simple launch.json configuration for Node.js would look like this:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "node",
            "request": "launch",
            "name": "Launch Program",
            "program": "${workspaceFolder}/app.js"
        }
    ]
}
  1. Start Debugging: To start debugging, you can click on the bug icon on the left sidebar, and then click on the green arrow at the top of the sidebar. You can now set breakpoints in your code by clicking on the space next to the line numbers.

Debugging TypeScript in the Browser​

You can also debug TypeScript directly in the browser. Here's how:

  1. Enable Source Maps: To debug TypeScript in the browser, you need to enable source maps in your tsconfig.json file. Source maps map your compiled JavaScript code back to your original TypeScript code. You can enable them by adding "sourceMap": true to your tsconfig.json file.

  2. Open Developer Tools: Open the developer tools in your browser (usually F12 or Command+Option+I on Mac), go to the "Sources" tab, and you should see your TypeScript files there. You can now set breakpoints and debug your code.

Wrapping Up​

Congratulations! You've now learned how to debug TypeScript in both VS Code and the browser. Remember, debugging is a powerful tool that can save you a lot of time when diagnosing and fixing issues in your code. Happy debugging!