Generate a random number of seven or eight digits

The JavaScript code below generates a random number of seven or eight characters.

function generateRandomNumber(lowerExtreme, upperExtreme) {
return Math.floor(Math.random() * (upperExtreme - lowerExtreme) + lowerExtreme);
}

var num = "" + generateRandomNumber(1000000,99999999);

$context.result.postMessage($context.result.LEVEL_INFO, "Random rUID: " + num);
$prop.set("MessageClip", "rUID", num);