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JavaScript jQuery Basics (2014) Creating a Password Confirmation Form Perform: Part 2

Rifqi Fahmi
Rifqi Fahmi
23,164 Points
Posted by Rifqi Fahmi
Rifqi Fahmi
23,164 Points

need little help here about function

in this javascript course we can see the teacher write function like this

function passwordEvent(){
    //Find out if password is valid  
    if(isPasswordValid()) {
      //Hide hint if valid
      $password.next().hide();
    } else {
      //else show hint
      $password.next().show();
    }
}

And he call the function in this function

$password.focus(passwordEvent).keyup(passwordEvent);

I am little forget about last lesson in javascript, I remember that whenever we call the function, we need to type the-function-name(). Why in this video he didn't type the parentheses after calling the function such as .......focus(passwordEvent)......

Maybe i am missing something in learning javascript, thanks :)

1 Answer

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

Hi Rifqi,

You're correct. When calling a function you need to put parentheses after the name. In this case though, we don't want to call the function right then and there.

If we have the following:

.focus(passwordEvent()) // wrong code

then that means the passwordEvent function will be called immediately when that code is reached and the return value of that function is what will be passed into the focus method which is not what we want to happen.

Instead we want to pass in a reference to the function (name only, no parentheses) so that the focus method can call this function for us anytime the element receives focus.

We're basically saying to the focus method, "Here's the name of the function that I want you to call whenever the element receives focus."

Rifqi Fahmi
Rifqi Fahmi
23,164 Points
Rifqi Fahmi
Rifqi Fahmi
23,164 Points

thanks jason, thats make myself clear :D

Fidel Severino
Fidel Severino
3,514 Points

Wow, thanks for that explanation. I was wondering the same thing. Very informative answer!