javascript - Why is the boolean undefined? - Stack Overflow

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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.

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.

• javascript
• undefined
• undefined-reference

Share Improve this question Follow asked Apr 17, 2012 at 10:59 dublintechdublintech 17.8k3131 gold badges8888 silver badges118118 bronze badges

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4 Answers 4

Sorted by: Reset to default 3

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);

You need to add this to refer to the object:

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

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

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

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()

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.

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