No Constant Condition

Disallows the use of a constant expression in conditional test.

Using a constant expression in a conditional test is often either a mistake or a temporary situation introduced during development and is not ready for production.

Invalid:

if (true) {}
if (2) {}
do {} while (x = 2); // infinite loop

Valid:

if (x) {}
if (x === 0) {}
do {} while (x === 2);