Javascript: Why do I put “()” after a variable when calling it in console.log?

Question

I'm working through examples in the ebook "eloquent javascript." On page 51, in the Functions chapter, in the Closure section, there's the following example:

function wrapValue2(n) {

  var localVariable = n; 
    return function() {
       return localVariable; 
  };
}

 var wrap2 = wrapValue2(3);
   console.log(wrap2());

As you can see in the last line of the code above, "console.log(wrap2());," the variable is being called inside of console.log. I was having some trouble re-writing this code until I realized there are parenthesis after the variable! Why would I put parenthesis after a variable?

Don't I only do that after a function?

Is this command using the variable as a function? If so, why?

Is it because the object contained within the variable is a function? That doesn't seem very likely.

Thanks in advance!

Answer 1

Exactly: those parentheses are used to call wrap2 , because it's a function.

You use

var wrap2 = wrapValue2(3);

And the function wrapValue2 returns another function.

So wrap2 is a function.

Answer 2

The function ...

function wrapValue2(n) {
  var localVariable = n; 
    return function() {
       return localVariable; 
  };
}

returns a function (see return function() ) ... that will need executed to get the answer.

Answer 3

因为wrap2将在最后作为函数，而wrapValue2返回的function不是value 。