Undefined

Question

Hello!

when I just ran this code below, (and I didn't type anything into the webconsole), however I got;

"hellojim"

undefined

1) It makes sense for it to return ''hellojim" , but in this case, what does 'undefined' mean (again, I just ran this code, I did not type anything into web console: jim.green().

2) When I call in the console: jim.green(jim); I get undefined and then on the second line, I get: "hellojim" My jim object has console.log( 'hello' + this.name); so the 'this' should bind to the object jim and return its name,so what does 'undefined' right before it print "hellojim" mean? I also get the same output when I type in the console: jim.green('jim');

<!DOCTYPE html>
 <html>

 <head>  
  </head>
  <body>


    <script>
    var jim = 
    { 'name' : 'jim',
    'skills': ['js', 'excel'],
    'favorite color' : 'green',
    green : function(){
    console.log( 'hello' + this.name);

    }


    };
    console.log(jim.green());           

    </script>
  </body>
</html>

Answer 1 · 2014-06-12T04:01:55Z

June 12, 2014 4:01am

I can't recall the order of the course, but undefined will be explained as the return value of the method that you called to log 'hellojim' to the console. Every method has a return value, and if it is not defined explicitly a method will return undefined.

An addition to my original answer, when you call console.log(jim.greet()); the first undefined is the console logging the return value from the greet() method, which is undefined since it's not specifically defined. The hellojim that prints afterward is the console.log() statement in the greet method in the object.

Answer 2 · 2014-06-13T02:10:06Z

June 13, 2014 2:10am

Thank Scott, the second paragraph makes everything clear to me. :)

Welcome to the Treehouse Community

Looking to learn something new?

orange sky

orange sky

Undefined

2 Answers

J Scott Erickson

J Scott Erickson

orange sky

orange sky