Tips and Tricks for Debugging Typescript Code

Debugging Typescript code can be a bit trickier than debugging regular JavaScript code, since the compiled code may not always match the original Typescript code. However, there are a few tools and techniques that can make debugging Typescript code easier.

Using the Typescript Compiler Flags

One way to make debugging Typescript code easier is by using the appropriate compiler flags. The --sourceMap flag generates source maps, which allow you to debug the original Typescript code rather than the compiled JavaScript code. The --inlineSourceMap flag includes the source map as a data URL in the compiled JavaScript file, which can be useful for debugging in certain environments.

The --inlineSources flag includes the original Typescript source code in the source map, which can be useful for debugging when the source maps are not available. However, this can increase the size of the compiled JavaScript file, so it should be used sparingly.

Using a Debugger

Most modern code editors and IDEs have built-in debuggers that can be used to debug Typescript code. These debuggers typically allow you to set breakpoints, step through code, and inspect variables.

To use a debugger, you will need to configure the debugger to use the source maps generated by the Typescript compiler. This typically involves specifying the location of the source maps and the root directory of the Typescript files.

Console Logging

Sometimes, using a debugger is not practical or possible, and in these cases, console logging can be a useful tool for debugging Typescript code. By inserting console.log statements into your code, you can print out the values of variables and expressions to the console, which can help you identify problems in your code.

Tips and Tricks

• Use type assertions to temporarily override the type of a variable. This can be useful for debugging when you suspect that the wrong type is being inferred.
• Use the --strict flag to enable additional type checking and catch more bugs at compile time.
• Use the --noEmitOnError flag to prevent the compiler from generating JavaScript code if there are type errors. This can be useful for catching type errors early on.

If you’re having a particularly difficult time debugging your code, you might consider using a debugger. Many code editors have built-in debuggers, or you can use a standalone debugger like the Chrome DevTools. Debuggers allow you to step through your code line by line, see the values of variables at different points in time, and even set breakpoints to pause the execution of your code.

Conclusion

Finally, don’t be afraid to ask for help. Whether it’s from coworkers, online communities like Stack Overflow, or a mentor, getting a fresh perspective on your code can often lead to a breakthrough in understanding what’s going wrong.

Exercises

To review these concepts, we will go through a series of exercises designed to test your understanding and apply what you have learned.

Consider the following code:

function add(a: number, b: number): number {
  return a + b;
}

console.log(add(1, '2'));

Consider the following code:

interface Point {
  x: number;
  y: number;
}

function printPoint(point: Point): void {
  console.log(`(${point.x}, ${point.y})`);
}

const point = { x: 1, y: 2, z: 3 };
printPoint(point);

Consider the following code:

function add(a: number, b: number): number {
  return a + b;
}

console.log(add(1, 2));

{
  "compilerOptions": {
    "strict": true
  }
}

function myFunction() {
  let x = 1;
  let y = 2;
  debugger; // execution will pause here, allowing you to inspect x and y
  let z = x + y;
}