Avoid using control flow statements in
finally blocks JS-0026
Bug risk
Major
2 years ago
—
2 years old
Unsafe usage of ReturnStatement.
617 }
618 finally
619 {
620 return;621 }
622}
623Unsafe usage of ReturnStatement.
76 }
77 finally
78 {
79 return;80 }
81}
82Unsafe usage of ReturnStatement.
32 }
33 finally
34 {
35 return;36 }
37}
38Unsafe usage of ReturnStatement.
381 }
382 finally
383 {
384 return;385 }
386}
387Unsafe usage of ReturnStatement.
96 }
97 finally
98 {
99 return;100 }
101}
102
Description
The usage of control flow statements like return, throw, break, and continue inside finally blocks is not recommended.
JavaScript will suspend the execution of any control flow statements in the try and/or catch blocks and will run the finally block first.
For example, a return within a finally block would override a return within the preceding try block, often leading to unexpected behavior.
Bad Practice
// We expect this function to return 1;
const foo = function() {
try {
return 1; // 1 is returned but suspended until finally block ends
} catch(err) {
return 2;
} finally {
throw new Error(); // Error was thrown before returning 1
}
}
Recommended
let foo = function() {
try {
return 1;
} catch(err) {
return 2;
} finally {
console.log("hola!");
}
};