51 lines
1.4 KiB
Plaintext
51 lines
1.4 KiB
Plaintext
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== Why is this an issue?
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The ECMAScript specification allows for creating block-level lexical declarations (`let`, `const`, `function`, and `class`) in any block statement or expression. However, when these declarations are made inside the `case` or `default` clause of a `switch` statement, they are not confined to the block of that `case` or `default` clause. Instead, they apply to the whole `switch` block but only get initialized when the cases are reached, which can lead to unexpected behavior.
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[source,javascript,diff-id=1,diff-type=noncompliant]
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----
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switch (foo) {
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case 1:
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let x = 1; // Noncompliant
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break;
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case 2:
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const y = 2; // Noncompliant
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break;
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case 3:
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function f() {} // Noncompliant
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break;
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case 4:
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class C {} // Noncompliant
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break;
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}
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----
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To fix this, you can create a nested block within each `case` or `default` clause, ensuring each declaration is properly scoped to its respective block.
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[source,javascript,diff-id=1,diff-type=compliant]
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----
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switch (foo) {
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case 1: {
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let x = 1;
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break;
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}
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case 2: {
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const y = 2;
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break;
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}
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case 3: {
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function f() {}
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break;
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}
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case 4: {
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class C {}
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break;
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}
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}
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----
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== Resources
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=== Documentation
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* MDN web docs - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/switch[switch]
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