no-case-declarations
NOTE: this rule is part of the
recommended rule set.Enable full set in
deno.json:{
"lint": {
"tags": ["recommended"]
}
}Enable full set using the Deno CLI:
deno lint --tags=recommended
Requires lexical declarations (let, const, function and class) in switch
case or default clauses to be scoped with brackets.
Without brackets in the case or default block, the lexical declarations are
visible to the entire switch block but only get initialized when they are
assigned, which only happens if that case/default is reached. This can lead to
unexpected errors. The solution is to ensure each case or default block is
wrapped in brackets to scope limit the declarations.
Invalid:
switch (choice) {
// `let`, `const`, `function` and `class` are scoped the entire switch statement here
case 1:
let a = "choice 1";
break;
case 2:
const b = "choice 2";
break;
case 3:
function f() {
return "choice 3";
}
break;
default:
class C {}
}
Valid:
switch (choice) {
// The following `case` and `default` clauses are wrapped into blocks using brackets
case 1: {
let a = "choice 1";
break;
}
case 2: {
const b = "choice 2";
break;
}
case 3: {
function f() {
return "choice 3";
}
break;
}
default: {
class C {}
}
}