eslint/no-extra-boolean-cast Correctness

✅ This rule is turned on by default.

🛠️💡 An auto-fix and a suggestion are available for this rule for some violations.

What it does

This rule disallows unnecessary boolean casts.

Why is this bad?

In contexts such as an if statement's test where the result of the expression will already be coerced to a Boolean, casting to a Boolean via double negation (!!) or a Boolean call is unnecessary.

Examples

Examples of incorrect code for this rule:

var foo = !!!bar;
var foo = Boolean(!!bar);

if (!!foo) {}
if (Boolean(foo)) {}

// with "enforceForLogicalOperands" option enabled
if (!!foo || bar) {}

Examples of correct code for this rule:

var foo = !bar;
var foo = Boolean(bar);

if (foo) {}
if (foo) {}

// with "enforceForLogicalOperands" option enabled
if (foo || bar) {}

How to use

To enable this rule in the CLI or using the config file, you can use:

CLI

oxlint --deny no-extra-boolean-cast

Config (.oxlintrc.json)

{
  "rules": {
    "no-extra-boolean-cast": "error"
  }
}

References

• Rule Source