eslint/no-constant-condition Correctness

✅ This rule is turned on by default.

What it does

Disallow constant expressions in conditions

Why is this bad?

A constant expression (for example, a literal) as a test condition might be a typo or development trigger for a specific behavior.

This rule disallows constant expressions in the test condition of:

• if, for, while, or do...while statement
• ?: ternary expression

Examples

Examples of incorrect code for this rule:

if (false) {
  doSomethingUnfinished();
}

if (new Boolean(x)) {
  doSomethingAlways();
}
if (x ||= true) {
  doSomethingAlways();
}

do {
  doSomethingForever();
} while (x = -1);

Examples of correct code for this rule:

if (x === 0) {
  doSomething();
}

while (typeof x === "undefined") {
  doSomething();
}

Options

checkLoops

{ type: "all" | "allExceptWhileTrue" | "none" | boolean, default: "allExceptWhileTrue" }

• "all" or true disallows constant expressions in loops
• "allExceptWhileTrue" disallows constant expressions in loops except while loops with expression true
• "none" or false allows constant expressions in loops

How to use

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

CLI

oxlint --deny no-constant-condition

Config (.oxlintrc.json)

{
  "rules": {
    "no-constant-condition": "error"
  }
}

References

• Rule Source