void

const output = void 1;
console.log(output);
// : undefined

void console.log("");
// : ""

void (function iife() {
  console.log("IIFE ");
})();
// : "IIFE "

void function test() {
  console.log("test ");
};
try {
  test();
} catch (e) {
  console.log("test ");
  // : "test "
}

void expression

void 2 === "2"; // (void 2) === '2', false 
void (2 === "2"); // void (2 === '2'), undefined 

function iife() {
  console.log("");
}(); // SyntaxError: Unexpected token ')'

function () {
  console.log("");
}(); // SyntaxError: Function statements require a function name

void function () {
  console.log("");
}();

// Logs ""

(function () {
  console.log("");
})();

void () => { console.log("iife!"); }(); // SyntaxError: Malformed arrow function parameter list

<a href="javascript:void(0);"></a>

<a href="javascript:void(document.body.style.backgroundColor='green');">
  
</a>

checkbox.onclick = () => doSomething();

checkbox.onclick = () => void doSomething();