A number of statements unconditionally exit a block of code. Any statements after that will not be executed and may be an error. The presence of unreachable code is usually a sign of a coding error.
function fn() {
x = 1;
return x;
x = 3; // this will never execute
}
This rule is aimed at detecting unreachable code. It produces an error when a statements in a block exist after a return, throw, break, or continue statement. The rule checks inside block statements and switch cases.