The difference between parentheses and parentheses when JS calls a function

The function name is actually a pointer to the body of the function
Without parentheses, it can be thought of as the complete information to view the function,
Without parentheses, the equivalent of passing in the function as a whole
Parentheses indicate that the code inside the function is called immediately (executed) (the code in the curly braces section)

Example 2:

Function Demo () {
Return 1
}
var A=demo
var B=demo ()
A is the demo function, B is 1

The difference between parentheses and parentheses when JS calls a function