Why would a JavaScript variable start with a dollar sign? A valid JavaScript identifier shuold must start with a letter, underscore (_), or dollar sign ($); subsequent characters can also be digits (0-9) Because JavaScript is case sensitive, letters include the characters "A" through "Z" (uppercase) and the characters "a" through "z" (lowercase)
What does the !! (double exclamation mark) operator do in JavaScript . . . Novice JavaScript developers need to know that the "not not" operator is using implicitly the original loose comparison method instead of the exact or operators and also the hidden cast operation that is happening behind the scenes and I show it in the example I provide