default-case-last
强制 switch 语句中的 default 子句位于最后
switch 语句可以选择性地包含一个 default 子句。
🌐 A switch statement can optionally have a default clause.
如果存在，它通常是最后一个从句，但不必如此。也允许将 default 从句放在所有 case 从句之前，或者放在中间的任何位置。其行为大致与放在最后一个从句时相同。default 块仍然只会在 case 从句中没有匹配时执行（包括在 default 之后定义的那些），但也可以从 default 从句“贯穿”到列表中的下一个从句。然而，这种流程并不常见，并且会让读者感到困惑。
🌐 If present, it’s usually the last clause, but it doesn’t need to be. It is also allowed to put the default clause before all case clauses, or anywhere between. The behavior is mostly the same as if it was the last clause. The default block will be still executed only if there is no match in the case clauses (including those defined after the default), but there is also the ability to “fall through” from the default clause to the following clause in the list. However, such flow is not common and it would be confusing to the readers.
即使没有“贯穿”逻辑，但在 case 子句之前或之间看到 default 子句仍然是意外的。按照惯例，它应当是最后一个子句。
🌐 Even if there is no “fall through” logic, it’s still unexpected to see the default clause before or between the case clauses. By convention, it is expected to be the last clause.
如果 switch 语句应该有一个 default 子句，最好将其定义为最后一个子句，这被认为是最佳做法。
🌐 If a switch statement should have a default clause, it’s considered a best practice to define it as the last clause.
规则详情
🌐 Rule Details
此规则强制 switch 语句中的 default 子句必须放在最后。
🌐 This rule enforces default clauses in switch statements to be last.
它仅适用于已经有 default 子句的 switch 语句。
🌐 It applies only to switch statements that already have a default clause.
此规则不强制要求存在 default 子句。如果你还想强制要求在 switch 语句中存在 default 子句，请参见 default-case。
🌐 This rule does not enforce the existence of default clauses. See default-case if you also want to enforce the existence of default clauses in switch statements.
此规则的错误代码示例：
🌐 Examples of incorrect code for this rule:
/*eslint default-case-last: "error"*/
switch (foo) {
default:
bar();
break;
case "a":
baz();
break;
}
switch (foo) {
case 1:
bar();
break;
default:
baz();
break;
case 2:
quux();
break;
}
switch (foo) {
case "x":
bar();
break;
default:
case "y":
baz();
break;
}
switch (foo) {
default:
break;
case -1:
bar();
break;
}
switch (foo) {
default:
doSomethingIfNotZero();
case 0:
doSomethingAnyway();
}
符合此规则的正确代码示例：
🌐 Examples of correct code for this rule:
/*eslint default-case-last: "error"*/
switch (foo) {
case "a":
baz();
break;
default:
bar();
break;
}
switch (foo) {
case 1:
bar();
break;
case 2:
quux();
break;
default:
baz();
break;
}
switch (foo) {
case "x":
bar();
break;
case "y":
default:
baz();
break;
}
switch (foo) {
case -1:
bar();
break;
}
if (foo !== 0) {
doSomethingIfNotZero();
}
doSomethingAnyway();
选项
🌐 Options
此规则没有选项。
🌐 This rule has no options.
相关规则
版本
此规则是在 ESLint v7.0.0-alpha.0 中引入。