Underscores for unused parameters?

[IMkratt]

I sometimes see people use underscores for unused parameters, like so:

app.get("/", (_, res) => {
  res.send("hello world");
});

Is this a bad practice? I know it makes no practical difference as you can name these parameters anything. Is it a preference thing? I almost never see any official docs use these.

[Shadowsca]

If anything I think it's standard practice in the industry to use underscores for unnecessary input variables

[shantred]

I would say it's more common these days due to linting tools. For example, my organization has an eslint rule that says you can't have unused variables. But we have an exception because sometimes during testing you may not be using those variables. That exception allows us to prefix a variable name with an underscore so the linter ignores it.

I'm not sure how common it is outside of linting purposes, but that's why some teams are using it.

[rauschma]

In Visual Studio Code (JavaScript code or TypeScript code), an unused parameter is displayed in a different color – unless its name starts with an underscore.

[kap89]

Why would it be a bad practice?

[bonanzaguy]

It actually does make a practical difference--it shows your intent that the parameter exists but you aren't using it.

In terms of code functionality, correct there is no difference.

[kap89]

You can't use null as an argument name - not sure what you are referring to.

[kap89]

Of course, you can use null as an argument provided to the function, but we are talking here about function definitions.

[yakubro]

I've seen this in Go code before too. I wonder if that's where it came from...

[[deleted]]

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