Error detected in Deno project's tsconfig.json file, spreading into other project files - yet code executes without issues?

Question

Error detected in Deno project's tsconfig.json file, spreading into other project files - yet code executes without issues?

I am working on a Deno project and need to utilize the ES2019 flatMap() method on an array. To do this, I have created a tsconfig.json file with the following configuration:

{
    "compilerOptions": {
        "target": "es5",
        "lib": [
            "es2019"
        ]
    }
}

After setting up the tsconfig.json file in this manner, I encountered 6 linter errors stating

Cannot find type definition file for 'cacheable-request'

. Is there a mistake in how I created the file or could it be conflicting with the Deno structure?

Within a module of my project where I intend to use flatMap(), I received the error:

Property 'flatMap' does not exist on type 'number[][]'. Should I modify the target library? Perhaps changing the `lib` compiler option to 'es2019' or later would help.

Although I have specified es2019 as the target library in my tsconfig file, the error message seems contradictory since the code actually works. It makes me wonder if I made an error in creating the tsconfig file that is preventing it from being recognized... but then again, the code successfully compiles to es2019.

Is there something crucial that I might be overlooking when configuring a tsconfig file for a Deno project to enable the usage of es2019 features?

javascript typescript visual-studio-code eslint deno

Answer 1

Answer №1

It seems that you don't need to include a tsconfig.json file in order to utilize ES2019 features in Deno. I recently experimented with the flatMap method in Deno version 1.9.0, and it worked smoothly:

// app.ts
const data = [1,2,3,[1,2,3],[1,2]].flatMap((_val, _index, _arr) => {
    return 1;
});

console.log(data);

deno run app.ts 
>> [ 1, 1, 1, 1, 1 ]

I didn't encounter any information suggesting that this feature was unavailable or problematic in earlier versions. Consider updating your Deno installation and removing the tsconfig.json file if you encounter issues.

Answer 2

It seems that you don't need to include a tsconfig.json file in order to utilize ES2019 features in Deno. I recently experimented with the flatMap method in Deno version 1.9.0, and it worked smoothly:

// app.ts
const data = [1,2,3,[1,2,3],[1,2]].flatMap((_val, _index, _arr) => {
    return 1;
});

console.log(data);

deno run app.ts 
>> [ 1, 1, 1, 1, 1 ]

I didn't encounter any information suggesting that this feature was unavailable or problematic in earlier versions. Consider updating your Deno installation and removing the tsconfig.json file if you encounter issues.

Error detected in Deno project's tsconfig.json file, spreading into other project files - yet code executes without issues?

Answer №1

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