1394123 - Property Accessors: No mention of what happens when a property is not present on an object

Status: RESOLVED WONTFIX

(Developer Documentation Graveyard :: JavaScript, defect, P5)

Description

[Jason Clark]

:: Developer Documentation Request

      Request Type: Correction
     Gecko Version: Trunk
 Technical Contact: 

:: Details

Property Accessors documentation (Javascript ref, operators) explains the use of dot notation and bracket notation for accessing properties of an object, but does not explain what occurs when no such property exists on the object.  Consider:

    var myObj = {foo: 1}

What does `myObj.bar` return?  What about `myObj['bar']`, any difference?  I *think* both return `undefined` (not certain, that's why I'm checking the docs), but someone coming from another language could expect `null` to be returned, or even an exception to be thrown.  Also, is there any mechanism available to intercept attempts to access such undefined properties, and act on them?

Comment 1

[BMO Automation]

MDN Web Docs' bug reporting has now moved to GitHub. From now on, please file content bugs at https://github.com/mdn/sprints/issues/ and platform bugs at https://github.com/mdn/kuma/issues/.