The void operator evaluates its argument and unconditionally returns undefined. It can be useful in pre-ECMAScript 5 environments, where undefined could be reassigned, but generally, its use makes code harder to understand.

Noncompliant Code Example

void (function() {
   ...
}());

Compliant Solution

(function() {
   ...
}());

Exceptions

No issue is raised when void 0 is used in place of undefined.

if (parameter === void 0) {...}