Why is the boolean undefined?

Question

In javascript I do:

var myObject = {
  myBoo: false,
  myMethod: function () {
     console.log("my method: "+ myBoo);
  }
}
console.log("myObject.myBoo=" + myObject.myBoo);
myObject.myMethod();

This outputs:

myObject.myBoo=false
ReferenceError: myBoo is not defined

Why is myBoo undefeind from myMethod's perspective?

Thanks.

Answer 1

This is because myBoo is not defined as a global variable, but rather as an object property. The proper way of accessing it in the myMethod function would therefore be:

console.log("my method: "+ this.myBoo);

Answer 2

You need to add this to refer to the object:

myMethod: function () {
    console.log("my method: "+ this.myBoo);
}

Here's a fiddle: http://jsfiddle.net/9xB83/

Here's a great article about this http://www.quirksmode.org/js/this.html .

Answer 3

myBoo is an attribute of the object hence you will have to access it in reference to the object itself.

it should be this.myBoo in the myMethod function()

Answer 4

Your function "myMethod" is trying to access local variable myBoo which doesn't exist in the context of your function! What you meant to do is use this.myBoo.