Debug deno on vscode

index.ts

/**
 * @description create a to recreate the fibonacci sequence and returns it into an array
 * @param n total of loops
 * @returns and array filled with fibonacci sequence
 * @example [0,1,1,2,3,5,8,13,21...]
 */
export function fibonashi(n: number): unknown[] {
	const a: number[] = [0, 1];
	if (n === 1) return [0];
	if (n === 2) return [0, 1];

	for (let i = 2; i < n; ++i) {
		a[i] = a[i - 1] + a[i - 2];
	}
	return a;
}

console.log(fibonashi(9));

launch.json

{
	"version": "0.2.0",
	"configurations": [
		{
			"request": "launch",
			"name": "Launch Program",
			"type": "node",
			"program": "${workspaceFolder}/index.ts", // replace to your main file
			"cwd": "${workspaceFolder}",
			"runtimeExecutable": "deno",
			"outputCapture": "std", // this will output things on DEBUG CONSOLE
			"runtimeArgs": [
				"run",
				"--unstable",
				"--inspect-brk", 
        // ^ important, see the quote on https://deno.land/manual@v1.19.1/getting_started/debugging_your_code#debugging-your-code
				"--allow-all"
			],
			"attachSimplePort": 9229
		}
	]
}

If you have errors at the key "type" in launch.json surely it is because you don't have anything to run the node debugger so I recommend you to install: https://marketplace.visualstudio.com/items?itemName=ms-vscode.js-debug-nightly