source map tutorial Archives

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I’m a detective on a mission to solve a mystery in a mansion. The mansion represents my JavaScript code, and the mystery is a bug I need to track down. Now, the mansion is enormous and has many rooms, just like how a large JavaScript file can have many lines of code. But here’s the twist: the map I have is actually of a blueprint, which represents my TypeScript code. TypeScript makes everything neat and organized but it’s not what’s actually in the mansion.

To solve the mystery efficiently, I need a special kind of map called a “source map.” This source map is like a decoder ring. When I enter a room in the mansion (JavaScript), the source map helps me instantly find the corresponding room on the blueprint (TypeScript). This way, I can see exactly where things went wrong in the original design.

To enable this map, I need to make a small tweak in my detective toolkit—my tsconfig.json file. I simply add "sourceMap": true under the compiler options. With this setting in place, every time I compile my TypeScript, a source map is created. It’s like having a side-by-side translation of my mansion to the blueprint.

Once enabled, I can use the source map in my browser’s developer tools. As I navigate through the mansion (JavaScript code) in the tools, the source map leads me back to the blueprint (TypeScript code), making it much easier to trace the mystery back to its source. It’s like having a GPS that guides me through the mansion, room by room, until I find the clue I need to solve the bug.

And there it is, the mystery solved, all thanks to my trusty source map. If this detective tale helped clarify the concept for you, consider sharing it with someone who might enjoy the journey too!

Enabling Source Maps

In my trusty toolkit, the tsconfig.json file, I ensure that "sourceMap": true is set under the compilerOptions. This is like preparing my detective gear before entering the mansion. Here’s how it looks:

{
  "compilerOptions": {
    "sourceMap": true,
    "outDir": "./dist"
  },
  "include": ["src/**/*"]
}

When I compile my TypeScript project using tsc, this configuration generates both a .js file and a .js.map file for each TypeScript file. The .js file is the mansion itself, whereas the .js.map file is the map that links back to the blueprint.

Using Source Maps in Practice

Suppose I have a simple TypeScript file, app.ts:

const greet = (name: string): string => {
  return `Hello, ${name}!`;
};

console.log(greet("World"));

After compiling, I’ll see these two files in my dist directory:

app.js
app.js.map

If I open my browser and inspect the console, and I encounter an error, the source map allows me to see the TypeScript code in the developer tools instead of the compiled JavaScript. This feature is like having a direct link back to the blueprint, making it much easier to debug.

Key Takeaways

Source Maps: They act as a bridge between your TypeScript (blueprint) and JavaScript (mansion), allowing for easier debugging and error tracing.
Ease of Debugging: With source maps enabled, browsers can show TypeScript code in developer tools, making it simpler to trace errors to their original TypeScript source.
Configuration: Enabling source maps requires a simple addition to your tsconfig.json, setting "sourceMap": true.

Tag: source map tutorial

How Do TypeScript Source Maps Simplify JavaScript Debugging?

Enabling Source Maps

Using Source Maps in Practice

Key Takeaways