Rule to disallow a duplicate case label (no-duplicate-case)
The "extends": "eslint:recommended"
property in a configuration file enables this rule.
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.
Rule Details
This rule disallows duplicate test expressions in case
clauses of switch
statements.
Examples of incorrect code for this rule:
/*eslint no-duplicate-case: "error"*/
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;
}
switch (a) {
case "1":
break;
case "2":
break;
case "1": // duplicate test expression
break;
default:
break;
}
Examples of correct code for this rule:
/*eslint no-duplicate-case: "error"*/
var a = 1,
one = 1;
switch (a) {
case 1:
break;
case 2:
break;
case 3:
break;
default:
break;
}
switch (a) {
case one:
break;
case 2:
break;
case 3:
break;
default:
break;
}
switch (a) {
case "1":
break;
case "2":
break;
case "3":
break;
default:
break;
}
Version
This rule was introduced in ESLint 0.17.0.