Millal ja milleks kasutatakse JavaScriptis undefined väärtust funktsiooni tagastustulemusena?

In JavaScript, the value undefined is often used as the return value of a function when the function does not explicitly return any value. This can be useful to indicate the absence of a result or when the function performs side effects but should not return data.

Examples of using undefined:

• The function does not contain a return statement or return without a value — by default, it returns undefined.
• Explicitly returning undefined to signal that the result is missing or not applicable.
• Used to check whether a parameter was passed or a result was computed.

Example:

function logMessage(msg) {
  console.log(msg);
  // No return, the function returns `undefined`
}

const result = logMessage('Hello');
console.log(result); // undefined

Thus, undefined serves as an indicator of the absence of a value or result.