Could you explain what the expression 'void 0' means in JavaScript?

In JavaScript, the expression void 0 is used to obtain the value undefined.

The void operator evaluates an expression but always returns undefined. For example:

console.log(void 0); // undefined

Why do people do this?

• In the past, the undefined value could be redefined, so void 0 reliably returns the true undefined.
• It is used to explicitly get undefined without the risk of the variable undefined being changed.

Thus, void 0 is a safe way to get undefined in any context.