eslint/no-duplicate-case Correctness

✅ This rule is turned on by default.

What it does

Disallow duplicate case labels

Why is this bad?

If a switch statement has duplicate test expressions in case clauses, it is likely that a programmer copied a case clause but forgot to change the test expression.

Examples

Examples of incorrect code for this rule:

var a = 1, one = 1;
switch (a) {
    case 1:
        break;
    case 2:
        break;
    case 1: // duplicate test expression
        break;
    default:
        break;
}

switch (a) {
    case one:
        break;
    case 2:
        break;
    case one: // duplicate test expression
        break;
    default:
        break;
}

Examples of correct code for this rule:

var a = 1,
    one = 1
switch (a) {
    case 1:
        break
    case 2:
        break
    default:
        break
}

switch (a) {
    case '1':
        break
    case '2':
        break
    default:
        break
}

How to use

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

Config (.oxlintrc.json)

{
    "rules": {
        "no-duplicate-case": "error"
    }
}

CLI

oxlint --deny no-duplicate-case

References

• Rule Source