10$: warn on 'typeof x === undefined'

[strager]

typeof x === undefined is always false. typeof returns a string. The programmer meant typeof x === "undefined" instead.

[Master-Helix]

Hi brother. Can I implement the changes required in this fix? Also, we have to implement the changes in C++ right?

[strager]

@Master-Helix Sure! Here's our contributor guide: https://quick-lint-js.com/contribute/ Let me know if you need more assistance.

[Master-Helix]

We have to make the changes everywhere in the repo for typeof x === undefined right?

[strager]

@Master-Helix What do you mean by 'everywhere in the repo'? For this task you definitely won't need to change (or even look at) most source files in quick-lint-js.

[Master-Helix]

You have tagged it under the C++ domain but it is related to JS files. And I can see the changes required are already there

[strager]

You have tagged it under the C++ domain but it is related to JS files.

quick-lint-js is a JavaScript checker/linter. quick-lint-js is written in C++. For this task you will be modifying C++ code.

And I can see the changes required are already there

I don't know what changes you're referring to. I pasted typeof x === undefined into the quick-lint-js playground and saw no diagnostics/warnings.

[Master-Helix]

You have tagged it under the C++ domain but it is related to JS files.

quick-lint-js is a JavaScript checker/linter. quick-lint-js is written in C++. For this task you will be modifying C++ code.

And I can see the changes required are already there

I don't know what changes you're referring to. I pasted typeof x === undefined into the quick-lint-js playground and saw no diagnostics/warnings.

I understood. Continuing on the fix

[Master-Helix]

You have tagged it under the C++ domain but it is related to JS files.

quick-lint-js is a JavaScript checker/linter. quick-lint-js is written in C++. For this task you will be modifying C++ code.

And I can see the changes required are already there

I don't know what changes you're referring to. I pasted typeof x === undefined into the quick-lint-js playground and saw no diagnostics/warnings.

I can see the red warning under typeof.

[strager]

I can see the red warning under typeof.

Hmm, did you make code changes? I don't see what you see:

const x = undefined;

if (typeof x === undefined) {
  console.log("x is undefined");
}

[Master-Helix]

No brother. I am running this directly from your master branch without making any changes. Can you confirm it ?

[vegerot]

I can see the red warning under typeof.

Hmm, did you make code changes? I don't see what you see:

const x = undefined;

if (typeof x === undefined) {
  console.log("x is undefined");
}

I can reproduce by typing typeof with the mathematical sans-serif small 𝗉.

const x = undefined;

if (ty𝗉eof x === undefined) {
  console.log("x is undefined");
}

[Master-Helix]

I guess the issue is with the font on the playground then ? The syntax should work irrespective of the font used

[strager]

@Master-Helix On the demo, can you run JSON.stringify(document.querySelector('textarea').textContent) in the browser's JS console and share the result? This will help rule out issues like what @vegerot mentioned.

[Master-Helix]

@Master-Helix On the demo, can you run JSON.stringify(document.querySelector('textarea').textContent) in the browser's JS console and share the result? This will help rule out issues like what @vegerot mentioned.

Sure.

[CoderMuffin]

I would be interested in attempting to resolve this issue unless either of @Master-Helix or @vegerot wanted to? (I am only asking because I saw the unassignment)

[strager]

@CoderMuffin Sure, you can tackle this task.

[CoderMuffin]

@strager Not sure if you get notified so I just wanted to let you know that I have submitted a pull request with the first draft for these changes :)